PLT-7503: Create Message Export Scheduled Task and CLI Command (#7612)

* Created message export scheduled task

* Added CLI command to immediately kick off an export job

* Added email addresses for users joining and leaving the channel to the export

* Added support for both MySQL and PostgreSQL

* Fixing gofmt error

* Added a new ChannelMemberHistory store and associated tests

* Updating the ChannelMemberHistory channel as users create/join/leave channels

* Added user email to the message export object so it can be included in the actiance export xml

* Don't fail to log a leave event if a corresponding join event wasn't logged

* Adding copyright notices

* Adding message export settings to daily diagnostics report

* Added System Console integration for message export

* Cleaned up TODOs

* Made batch size configurable

* Added export from timestamp to CLI command

* Made ChannelMemberHistory table updates best effort

* Added a context-based timeout option to the message export CLI

* Minor PR updates/improvements

* Removed unnecessary fields from MessageExport object to reduce query overhead

* Removed JSON functions from the message export query in an effort to optimize performance

* Changed the way that channel member history queries and purges work to better account for edge cases

* Fixing a test I missed with the last refactor

* Added file copy functionality to file backend, improved config validation, added default config values

* Fixed file copy tests

* More concise use of the testing libraries

* Fixed context leak error

* Changed default export path to correctly place an 'export' directory under the 'data' directory

* Can't delete records from a read replica

* Fixed copy file tests

* Start job workers when license is applied, if configured to do so

* Suggestions from the PR

* Moar unit tests

* Fixed test imports

store/storetest/store.go

@@ -19,29 +19,30 @@ func NewStoreChannel(result store.StoreResult) store.StoreChannel {
 
 // Store can be used to provide mock stores for testing.
 type Store struct {
-	TeamStore             mocks.TeamStore
-	ChannelStore          mocks.ChannelStore
-	PostStore             mocks.PostStore
-	UserStore             mocks.UserStore
-	AuditStore            mocks.AuditStore
-	ClusterDiscoveryStore mocks.ClusterDiscoveryStore
-	ComplianceStore       mocks.ComplianceStore
-	SessionStore          mocks.SessionStore
-	OAuthStore            mocks.OAuthStore
-	SystemStore           mocks.SystemStore
-	WebhookStore          mocks.WebhookStore
-	CommandStore          mocks.CommandStore
-	CommandWebhookStore   mocks.CommandWebhookStore
-	PreferenceStore       mocks.PreferenceStore
-	LicenseStore          mocks.LicenseStore
-	TokenStore            mocks.TokenStore
-	EmojiStore            mocks.EmojiStore
-	StatusStore           mocks.StatusStore
-	FileInfoStore         mocks.FileInfoStore
-	ReactionStore         mocks.ReactionStore
-	JobStore              mocks.JobStore
-	UserAccessTokenStore  mocks.UserAccessTokenStore
-	PluginStore           mocks.PluginStore
+	TeamStore                 mocks.TeamStore
+	ChannelStore              mocks.ChannelStore
+	PostStore                 mocks.PostStore
+	UserStore                 mocks.UserStore
+	AuditStore                mocks.AuditStore
+	ClusterDiscoveryStore     mocks.ClusterDiscoveryStore
+	ComplianceStore           mocks.ComplianceStore
+	SessionStore              mocks.SessionStore
+	OAuthStore                mocks.OAuthStore
+	SystemStore               mocks.SystemStore
+	WebhookStore              mocks.WebhookStore
+	CommandStore              mocks.CommandStore
+	CommandWebhookStore       mocks.CommandWebhookStore
+	PreferenceStore           mocks.PreferenceStore
+	LicenseStore              mocks.LicenseStore
+	TokenStore                mocks.TokenStore
+	EmojiStore                mocks.EmojiStore
+	StatusStore               mocks.StatusStore
+	FileInfoStore             mocks.FileInfoStore
+	ReactionStore             mocks.ReactionStore
+	JobStore                  mocks.JobStore
+	UserAccessTokenStore      mocks.UserAccessTokenStore
+	PluginStore               mocks.PluginStore
+	ChannelMemberHistoryStore mocks.ChannelMemberHistoryStore
 }
 
 func (s *Store) Team() store.TeamStore                         { return &s.TeamStore }
@@ -67,12 +68,15 @@ func (s *Store) Reaction() store.ReactionStore                 { return &s.React
 func (s *Store) Job() store.JobStore                           { return &s.JobStore }
 func (s *Store) UserAccessToken() store.UserAccessTokenStore   { return &s.UserAccessTokenStore }
 func (s *Store) Plugin() store.PluginStore                     { return &s.PluginStore }
-func (s *Store) MarkSystemRanUnitTests()                       { /* do nothing */ }
-func (s *Store) Close()                                        { /* do nothing */ }
-func (s *Store) DropAllTables()                                { /* do nothing */ }
-func (s *Store) TotalMasterDbConnections() int                 { return 1 }
-func (s *Store) TotalReadDbConnections() int                   { return 1 }
-func (s *Store) TotalSearchDbConnections() int                 { return 1 }
+func (s *Store) ChannelMemberHistory() store.ChannelMemberHistoryStore {
+	return &s.ChannelMemberHistoryStore
+}
+func (s *Store) MarkSystemRanUnitTests()       { /* do nothing */ }
+func (s *Store) Close()                        { /* do nothing */ }
+func (s *Store) DropAllTables()                { /* do nothing */ }
+func (s *Store) TotalMasterDbConnections() int { return 1 }
+func (s *Store) TotalReadDbConnections() int   { return 1 }
+func (s *Store) TotalSearchDbConnections() int { return 1 }
 
 func (s *Store) AssertExpectations(t mock.TestingT) bool {
 	return mock.AssertExpectationsForObjects(t,
@@ -98,6 +102,7 @@ func (s *Store) AssertExpectations(t mock.TestingT) bool {
 		&s.ReactionStore,
 		&s.JobStore,
 		&s.UserAccessTokenStore,
+		&s.ChannelMemberHistoryStore,
 		&s.PluginStore,
 	)
 }