GH-18288: Allow configuring unsafe-eval and unsafe-inline (#18801)

* GH-18288: Allow configuring unsafe-eval and unsafe-inline

* Add developer flags to telemetry

* wip

* wip

* Refactor based on review

* Refactor based on review

* fix expected vs. actual in assert.Equal

* Add unit tests, rework to check only supported flags.

* Update model/config.go

Co-authored-by: Jesse Hallam <jesse@thehallams.ca>

* Fix failing tests

* Refactor based on review

* Refactor based on review

* Refactor based on review

Co-authored-by: Jesse Hallam <jesse.hallam@gmail.com>
Co-authored-by: Jesse Hallam <jesse@thehallams.ca>

model/config.go

@@ -106,6 +106,7 @@ const (
 	ServiceSettingsDefaultListenAndAddress = ":8065"
 	ServiceSettingsDefaultGfycatAPIKey     = "2_KtH_W5"
 	ServiceSettingsDefaultGfycatAPISecret  = "3wLVZPiswc3DnaiaFoLkDvB4X0IV6CpMkj4tf2inJRsBY6-FnkT08zGmppWFgeof"
+	ServiceSettingsDefaultDeveloperFlags   = ""
 
 	TeamSettingsDefaultSiteName              = "Mattermost"
 	TeamSettingsDefaultMaxUsersPerTeam       = 50
@@ -302,6 +303,7 @@ type ServiceSettings struct {
 	RestrictLinkPreviews                              *string  `access:"site_posts"`
 	EnableTesting                                     *bool    `access:"environment_developer,write_restrictable,cloud_restrictable"`
 	EnableDeveloper                                   *bool    `access:"environment_developer,write_restrictable,cloud_restrictable"`
+	DeveloperFlags                                    *string  `access:"environment_developer"`
 	EnableOpenTracing                                 *bool    `access:"write_restrictable,cloud_restrictable"`
 	EnableSecurityFixAlert                            *bool    `access:"environment_smtp,write_restrictable,cloud_restrictable"`
 	EnableInsecureOutgoingConnections                 *bool    `access:"environment_web_server,write_restrictable,cloud_restrictable"`
@@ -416,6 +418,10 @@ func (s *ServiceSettings) SetDefaults(isUpdate bool) {
 		s.EnableDeveloper = NewBool(false)
 	}
 
+	if s.DeveloperFlags == nil {
+		s.DeveloperFlags = NewString("")
+	}
+
 	if s.EnableOpenTracing == nil {
 		s.EnableOpenTracing = NewBool(false)
 	}