Fix some bugs in BAMBI & improve PR reviewer experience

[khyatimahendru]

• Preserve order of keys in the file on disk while merge to reduce number of changes in diff.
• Update timestamp when a device property changes.
• Fix for the reported bugs:
  • Site metadata tags get imported with square brackets when using the BAMBI add-on. Brackets should be removed.
  • Empty discovery block should be retained, currently it gets removed if empty.
  • testing.targets.invalid.target_value changes from array to string. Handle to retain array.
  • Point ref gets changed from string to integer, this could potentially break the config. It should not be auto-casted to a number
  • Handle exception for read from invalid json file