Add config flow to HLK-SW16 (#37190)

* Add config flow to HLK-SW16

* Use entry_id for unique_id

* Add options update capability

* Refactor entry_id under domain

* Remove name from config

* Set options

* Remove options flow

* remove unneccesary else block from validate_input and move domain cleanup to async_unload_entry

* Add tests and config import

* Add back config schema

* Remove config import

* Refactor unload

* Add back config import

* Update coveragerc

* Don't mock validate_input

* Test duplicate configs

* Add import test

* Use patch for timeout test

* Use mock for testing timeout

* Use MockSW16Client for tests

* Check mock_calls count

* Remove unused NameExists exception

* Remove title from strings.json

* Mock setup for import test

* Set PARALLEL_UPDATES for switch

* Move hass.data.setdefault(DOMAIN, {}) to async_setup_entry