[MM-38216] Add API endpoint and adapt search to allow multi-team search (#18371)

* Add API endpoint and adapt search to allow multi-team search

* Refactor handler, refactor sql query to use squirrel, rename app and store functions and add tests

* Fix lint

* Fix search engines and remove unneeded comments

* Fix test

* Remove user from channel after test

app/file.go

@@ -1333,7 +1333,7 @@ func (a *App) SearchFilesInTeamForUser(c *request.Context, terms string, userId
 		case errors.As(nErr, &appErr):
 			return nil, appErr
 		default:
-			return nil, model.NewAppError("SearchPostsInTeamForUser", "app.post.search.app_error", nil, nErr.Error(), http.StatusInternalServerError)
+			return nil, model.NewAppError("SearchFilesInTeamForUser", "app.post.search.app_error", nil, nErr.Error(), http.StatusInternalServerError)
 		}
 	}