Add Asuswrt Config Flow and Scanner Entities (#46468)

* Add Asuswrt config flow (#43948)

* Add AsusWrt Scanner Entity (#44759)

* Add Scanner Entity

- device tracker entity changed from "DeviceScanner" to "ScannerEntity"
- sensors recoded to use "router" class
- config entry review to allow multiple entity (for future use)

* Force checks

* Removed new option and change sensors

* Update test_sensor.py

* Requested changes

* Removed router unique-id

* Update last_activity attr only when available

* Add Options for AsusWRT Scanner Entity (#44808)

* Add Asuswrt config flow (#43948)

* Add AsusWrt Scanner Entity (#44759)

* Add Scanner Entity

- device tracker entity changed from "DeviceScanner" to "ScannerEntity"
- sensors recoded to use "router" class
- config entry review to allow multiple entity (for future use)

* Force checks

* Removed new option and change sensors

* Update test_sensor.py

* Requested changes

* Removed router unique-id

* Update last_activity attr only when available

* Add Options for Scanner Entity

* Fix isort

* Removed "Track New" option

* Add Options for Scanner Entity

* Fix isort

* Removed "Track New" option

* Add test for all the options in the config flow