XYZ-37: Advanced Permissions Phase 1 Backend. (#8159)

* XYZ-13: Update Permission and Role structs to new design.

* XYZ-10: Role store.

* XYZ-9/XYZ-44: Roles API endpoints and WebSocket message.

* XYZ-8: Switch server permissions checks to store backed roles.

* XYZ-58: Proper validation of roles where required.

* XYZ-11/XYZ-55: Migration to store backed roles from policy config.

* XYZ-37: Update unit tests to work with database roles.

* XYZ-56: Remove the "guest" role.

* Changes to SetDefaultRolesFromConfig.

* Short-circuit the store if nothing has changed.

* Address first round of review comments.

* Address second round of review comments.

api4/post_test.go

@@ -136,14 +136,12 @@ func testCreatePostWithOutgoingHook(
 	defer func() {
 		th.App.UpdateConfig(func(cfg *model.Config) { cfg.ServiceSettings.EnableOutgoingWebhooks = enableOutgoingHooks })
 		th.App.UpdateConfig(func(cfg *model.Config) { cfg.ServiceSettings.EnableOnlyAdminIntegrations = enableAdminOnlyHooks })
-		th.App.SetDefaultRolesBasedOnConfig()
 		th.App.UpdateConfig(func(cfg *model.Config) {
 			cfg.ServiceSettings.AllowedUntrustedInternalConnections = &allowedInternalConnections
 		})
 	}()
 	th.App.UpdateConfig(func(cfg *model.Config) { cfg.ServiceSettings.EnableOutgoingWebhooks = true })
 	th.App.UpdateConfig(func(cfg *model.Config) { *cfg.ServiceSettings.EnableOnlyAdminIntegrations = true })
-	th.App.SetDefaultRolesBasedOnConfig()
 	th.App.UpdateConfig(func(cfg *model.Config) {
 		*cfg.ServiceSettings.AllowedUntrustedInternalConnections = "localhost 127.0.0.1"
 	})
@@ -496,14 +494,11 @@ func TestUpdatePost(t *testing.T) {
 		utils.SetIsLicensed(isLicensed)
 		utils.SetLicense(license)
 		th.App.UpdateConfig(func(cfg *model.Config) { *cfg.ServiceSettings.AllowEditPost = allowEditPost })
-		th.App.SetDefaultRolesBasedOnConfig()
 	}()
 	utils.SetIsLicensed(true)
 	utils.SetLicense(&model.License{Features: &model.Features{}})
 	utils.License().Features.SetDefaults()
-
 	th.App.UpdateConfig(func(cfg *model.Config) { *cfg.ServiceSettings.AllowEditPost = model.ALLOW_EDIT_POST_ALWAYS })
-	th.App.SetDefaultRolesBasedOnConfig()
 
 	post := &model.Post{ChannelId: channel.Id, Message: "zz" + model.NewId() + "a"}
 	rpost, resp := Client.CreatePost(post)
@@ -581,14 +576,12 @@ func TestPatchPost(t *testing.T) {
 		utils.SetIsLicensed(isLicensed)
 		utils.SetLicense(license)
 		th.App.UpdateConfig(func(cfg *model.Config) { *cfg.ServiceSettings.AllowEditPost = allowEditPost })
-		th.App.SetDefaultRolesBasedOnConfig()
 	}()
 	utils.SetIsLicensed(true)
 	utils.SetLicense(&model.License{Features: &model.Features{}})
 	utils.License().Features.SetDefaults()
 
 	th.App.UpdateConfig(func(cfg *model.Config) { *cfg.ServiceSettings.AllowEditPost = model.ALLOW_EDIT_POST_ALWAYS })
-	th.App.SetDefaultRolesBasedOnConfig()
 
 	post := &model.Post{
 		ChannelId:    channel.Id,