[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

store/storetest/mocks/PostStore.go

@@ -867,8 +867,8 @@ func (_m *PostStore) Search(teamID string, userID string, params *model.SearchPa
 	return r0, r1
 }
 
-// SearchPostsInTeamForUser provides a mock function with given fields: paramsList, userID, teamID, page, perPage
-func (_m *PostStore) SearchPostsInTeamForUser(paramsList []*model.SearchParams, userID string, teamID string, page int, perPage int) (*model.PostSearchResults, error) {
+// SearchPostsForUser provides a mock function with given fields: paramsList, userID, teamID, page, perPage
+func (_m *PostStore) SearchPostsForUser(paramsList []*model.SearchParams, userID string, teamID string, page int, perPage int) (*model.PostSearchResults, error) {
 	ret := _m.Called(paramsList, userID, teamID, page, perPage)
 
 	var r0 *model.PostSearchResults