* Do not write old state sharing availability topic
* Add a test
* Support for all availability topics
* delay async_write_ha_state till last callback
* Process write req after processing callback jobs
* Do not count subscription callbacks
* Simplify
* Stale docsting
* No topic needed for delays state write
* No need to clear when reloading
* Move test to test_mixins.py
* Only set up sensor platform for test
* move imports to top-level in mqtt server
* move imports to top-level in mqtt configflow
* move imports to top-level in mqtt init
* move imports to top-level in mqtt vacuum
* move imports to top-level in mqtt light
* Recreate component if discovery info is changed
* Update component instead of remove+add
* Set name and unique_id in __init__
* Update unit test
* Cleanup
* More cleanup
* Refactor according to review comments
* Change discovery_hash
* Review comments, add tests
* Fix handling of value_template