[pgAdmin][RM-6460]: Need a mechanism to detect a corrupt/broken config DB file.

Please find the attached patch for RM-6460:  Need a mechanism to detect a corrupt/broken config DB file.

1. Added checks if all tables added in the model are present in SQLite DB or not.

2. If migrations fail it will backup older file and try migrations with the newly created file. 

(User will get notification on UI for the location of the backup file and newly created.)

3. If the user deleted any table from SQLite DB pgAdmin will not run on the next restart and it will add the missing table list in the logs.