PLT-4403 Add server-based channel autocomplete, search and paging (#4585)

* Add more channel paging API

* Add channel paging support to client

* Add DB channel search functions

* Add API for searching more channels

* Add more channel search functionality to client

* Add API for autocompleting channels

* Add channel autocomplete functionality to the client

* Move to be deprecated APIs to their own file

* Final clean-up

* Fixes related to feedback

* Localization changes

* Add unit as suffix to timeout constants

store/sql_user_store.go

@@ -1120,7 +1120,7 @@ func (us SqlUserStore) Search(teamId string, term string, options map[string]boo
 				SEARCH_CLAUSE
 				INACTIVE_CLAUSE
 				ORDER BY Username ASC
-			LIMIT 50`
+			LIMIT 100`
 		} else {
 			searchQuery = `
 			SELECT
@@ -1264,7 +1264,7 @@ func (us SqlUserStore) performSearch(searchQuery string, term string, options ma
 		term = strings.Join(splitTerm, " ")
 
 		searchType = convertMySQLFullTextColumnsToPostgres(searchType)
-		searchClause := fmt.Sprintf("AND (%s) @@  to_tsquery(:Term)", searchType)
+		searchClause := fmt.Sprintf("AND (%s) @@  to_tsquery('simple', :Term)", searchType)
 		searchQuery = strings.Replace(searchQuery, "SEARCH_CLAUSE", searchClause, 1)
 	} else if utils.Cfg.SqlSettings.DriverName == model.DATABASE_DRIVER_MYSQL {
 		splitTerm := strings.Fields(term)