Adding the new search engine abstraction (#13304)

* WIP

* Adding bleve to go modules

* WIP

* Adding missing files from searchengine implementation

* WIP

* WIP

* WIP

* WIP

* WIP

* WIP

* User and channel indexing and searches implemented

* Make bleve tests run with in-memory indexes

* Implement post index and deletion tests

* Initial commits for the search layer

* Removing unnecesary indexing

* WIP

* WIP

* More fixes for tests

* Adding the search layer

* Finishing the migration of searchers to the layer

* Removing unnecesary code

* Allowing multiple engines active at the same time

* WIP

* Add simple post search

* Print information when using bleve

* Adding some debugging to understand better how the searches are working

* Making more dynamic config of search engines

* Add post search basics

* Adding the Purge API endpoint

* Fixing bleve config updates

* Adding missed file

* Regenerating search engine mocks

* Adding missed v5 to modules imports

* fixing i18n

* Fixing some test around search engine

* Removing all bleve traces

* Cleaning up the vendors directory and go.mod/go.sum files

* Regenerating timer layer

* Adding properly the license

* Fixing govet shadow error

* Fixing some tests

* Fixing TestSearchPostsFromUser

* Fixing another test

* Fixing more tests

* Fixing more tests

* Removing SearchEngine redundant text from searchengine module code

* Fixing some reindexing problems in members updates

* Fixing tests

* Addressing PR comments

* Reverting go.mod and go.sum

* Addressing PR comments

* Fixing tests compilation

* Fixing govet

* Adding search engine stop method

* Being more explicit on where we use includeDeleted

* Adding GetSqlSupplier test helper method

* Mocking elasticsearch start function

* Fixing tests

Co-authored-by: Miguel de la Cruz <miguel@mcrx.me>
Co-authored-by: mattermod <mattermod@users.noreply.github.com>

app/options.go

@@ -78,8 +78,8 @@ func StartMetrics(s *Server) error {
 	return nil
 }
 
-func StartElasticsearch(s *Server) error {
-	s.startElasticsearch = true
+func StartSearchEngine(s *Server) error {
+	s.startSearchEngine = true
 
 	return nil
 }
@@ -104,7 +104,7 @@ func ServerConnector(s *Server) AppOption {
 		a.cluster = s.Cluster
 		a.compliance = s.Compliance
 		a.dataRetention = s.DataRetention
-		a.elasticsearch = s.Elasticsearch
+		a.searchEngine = s.SearchEngine
 		a.ldap = s.Ldap
 		a.messageExport = s.MessageExport
 		a.metrics = s.Metrics