[FIX] format

[IMP] format

[IMP] unit test

[IMP] unit test

* Separate models by file
* Add `import_synchronizer`
* Add `export_synchronizer`
* Add `delete_synchronizer`
* Add `mapper`
* Add `fail_date` to abstract bind, remove state
* Add `dns.record.type` model and default data
* Add external date field handling to binder
* Rename `dns.domain` to `dns.zone`
* Remove `line` field from `dns.record`
* Change inheritance structure, add a `{model_name}.bind` framework
* Add security
* Code cleanup
* Add test coverage
* Don't cover test assets
* Change bind field to `odoo_id` to ease future migration
* Improve ReadMe

[IMP] connector_dns: Code and test improvements

* Require zone in record
* Fix action names in backend, zone, record
* Remove states from backend and zone

[FIX] connector_dns: Build and functional errors

* Add empty group in connector settings for DNS

[ADD] connector_dns: DNS Connector settings view