refactor: cut off helper

- Merge HelperApp into Auth
- Move Auth & UserSession into daemon
- Simplify Auth, remove redundant logics

This commit largely simplify the code.

Note that the function of starting sessions other than treeland will
temporarily not work after this commit, due to some wrongly designed
obsolete code. This will be fixed soon in the next commit.

Author: calsys456

src/CMakeLists.txt

@@ -3,6 +3,4 @@ if (QT_KNOWN_POLICY_QTP0001)
 endif()
 
 add_subdirectory(common)
-add_subdirectory(auth)
 add_subdirectory(daemon)
-add_subdirectory(helper)