Add unit test as friend class for InternalDataStore

Conflicts:
	You-DataStore/internal/internal_datastore.h
Checks private variable for Post_Basic_Test
Move tests for get method to top, as it will be used by other methods for test assertions
Add a new dummy task for InternalDataStore unit test
Add more assertions for post duplicate id unit test
Add more assertions to put basic test
Add more assertions to Put_FalseId_Test
Add more assertions to basic erase test