PLT-3695 refactoring to use sql_upgrader (#3788)

* PLT-3695 unitying upgrade support

* PLT-3695 refactoring to use sql_upgrader

* Fixing unit test

* Adding 3.3 to 3.4

* Fixing upgrading

* Seperating DB schema from version.go

* Fixing upgrade cmd

* Moving to const for exit codes

* remving old unused code

store/sql_preference_store.go

@@ -32,9 +32,6 @@ func NewSqlPreferenceStore(sqlStore *SqlStore) PreferenceStore {
 	return s
 }
 
-func (s SqlPreferenceStore) UpgradeSchemaIfNeeded() {
-}
-
 func (s SqlPreferenceStore) CreateIndexesIfNotExists() {
 	s.CreateIndexIfNotExists("idx_preferences_user_id", "Preferences", "UserId")
 	s.CreateIndexIfNotExists("idx_preferences_category", "Preferences", "Category")