Description of change

TDL 19957 update dict based implementation to class based

Changed dict-based implementation to class-based implementation.
Created functionality-wise separate files - schema, discover, sync, streams.
Moved logic of REST API call and error handling to client.py.
Created class for incremental, full_table sync.
Created parent class and class for each stream.
Added details code comments for each function.
Added detailed unit test case.
Removed unnecessary unit test case.
Added implementation to write separate bookmark for child and parent stream.
Tap use a minimum bookmark among the selected parent and its child stream.
Tap write maximum bookmark for all selected parents and its child's stream
Tap write all child records of newly updated parent records.
Tap write replication key value of parent's record in the state of child stream.
Split landings into submitted_landings and unsubmitted_landings and introduced a new replication key for both.

Manual QA steps