MM-8796: Full implementation of "Schemes" in Store/Model/App layers. (#8357)

* Add Scheme model and stub store.

* Port ChannelStore to be Scheme aware.

* Make almost all the API/APP layer work with ChannelSchemes.

Only thing still hacky is UpdateChannelMemberRoles().

* Add basic SchemeStore implementation.

* Migrate UpdateChannelMemberRoles properly and fix tests.

* Update store tests and mocks so they work.

* Include creating default roles in Scheme create store function.

* Implement role deletion and start scheme deletion.

* Only use non-deleted roles for authorization.

* Add GetByScheme method to Team store.

* Add GetChannelsByScheme.

* Update store mocks.

* Implement scheme deletion in the store.

* Rename is valid function.

* Add offset and limit to queries to fetch teams and channels by scheme.

* Fix queries.

* Implement scheme awareness in Team store and add a migration.

* Tidy up ChannelStore mapping functions and add exhaustive unit tests.

* Add all missing i18n.

* Proper tests for TeamStore internal functions and fix them.

* Make additional TeamMember fields nullable.

* Make new ChannelMember fields nullable.

* Create new nullable columns without defaults.

* Make new fields in large tables nullalble.

* Fix empty list of TeamMembers.

* Deduplicate SQL queries.

* Fix spelling.

* Fix review comment.

* More review fixes.

* More review fixes.

model/team.go

@@ -26,20 +26,21 @@ const (
 )
 
 type Team struct {
-	Id                 string `json:"id"`
-	CreateAt           int64  `json:"create_at"`
-	UpdateAt           int64  `json:"update_at"`
-	DeleteAt           int64  `json:"delete_at"`
-	DisplayName        string `json:"display_name"`
-	Name               string `json:"name"`
-	Description        string `json:"description"`
-	Email              string `json:"email"`
-	Type               string `json:"type"`
-	CompanyName        string `json:"company_name"`
-	AllowedDomains     string `json:"allowed_domains"`
-	InviteId           string `json:"invite_id"`
-	AllowOpenInvite    bool   `json:"allow_open_invite"`
-	LastTeamIconUpdate int64  `json:"last_team_icon_update,omitempty"`
+	Id                 string  `json:"id"`
+	CreateAt           int64   `json:"create_at"`
+	UpdateAt           int64   `json:"update_at"`
+	DeleteAt           int64   `json:"delete_at"`
+	DisplayName        string  `json:"display_name"`
+	Name               string  `json:"name"`
+	Description        string  `json:"description"`
+	Email              string  `json:"email"`
+	Type               string  `json:"type"`
+	CompanyName        string  `json:"company_name"`
+	AllowedDomains     string  `json:"allowed_domains"`
+	InviteId           string  `json:"invite_id"`
+	AllowOpenInvite    bool    `json:"allow_open_invite"`
+	LastTeamIconUpdate int64   `json:"last_team_icon_update,omitempty"`
+	SchemeId           *string `json:"scheme_id"`
 }
 
 type TeamPatch struct {