Add PWM Dimmer multi-press and ledmask support

[pcdiem]

Description:

Restructure PWM Dimmer to support multi-press buttons.

Make PWM Dimmer function button hold time a constant .5 seconds allowing SetOption32 value to be used for determining hold time for non-PWM Dimmer functions.

Add support for ledmask command to specify which LEDs are used to indicate the brightness. LEDs cooresponding to unset bits in ledmask can be used for other purposes.

Add support for dimmer switches with no local load (no relay and no PWM - all buttons control remote devices).

Related issue (if applicable): fixes #

Checklist:

• The pull request is done against the latest dev branch
• Only relevant files were touched
• Only one feature/fix was added per PR.
• The code change is tested and works on Tasmota core ESP8266 V.2.7.4.3
• The code change is tested and works on core ESP32 V.1.12.2
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass