Rebuild channel index (#26080)

* WIP

* Added rebuild channels index functionality

* Added rough logic to send message to all sysadmins

* WIP

* WIP

* WIP

* Cleanup

* i18n fix

* reading through all pages of system admins

* Fixed webapp style

* i18n fix

* Added help text

* i18n fix

* i18n update

* Updated system console button action

* Updated snapshots

* some cleanup

* Updated snapshot

* Update server/channels/app/server.go

Co-authored-by: Daniel Espino García <larkox@gmail.com>

* fixed typo

* Refactoring to improve readibility

* moved index check to API later during config update

* Added some docs

* Updated get system bot

---------

Co-authored-by: Daniel Espino García <larkox@gmail.com>

server/platform/services/searchengine/bleveengine/bleve.go

@@ -292,6 +292,10 @@ func (b *BleveEngine) PurgeIndexes(rctx request.CTX) *model.AppError {
 	return b.openIndexes()
 }
 
+func (b *BleveEngine) PurgeIndexList(rctx request.CTX, indexes []string) *model.AppError {
+	return model.NewAppError("Bleve.PurgeIndex", "bleveengine.purge_list.not_implemented", nil, "not implemented", http.StatusNotFound)
+}
+
 func (b *BleveEngine) DataRetentionDeleteIndexes(rctx request.CTX, cutoff time.Time) *model.AppError {
 	return nil
 }
@@ -331,3 +335,7 @@ func (b *BleveEngine) UpdateConfig(cfg *model.Config) {
 	}
 	b.cfg = cfg
 }
+
+func (b *BleveEngine) IsChannelsIndexVerified() bool {
+	return true
+}