KNX add support for Dimmer and Colour

[barbudor]

Description:

Related issue (if applicable): fixes #11733

Add support for absolute dimmer and colour control with the following datapoint:

Light type | Dimmer (Bright)   | Color                     |
-----------|-------------------|---------------------------|
Single     | DPT_Scaling 5.001 | not supported +           |
CT         | DPT_Scaling 5.001 | not supported  +          |
RGB        | DPT_Scaling 5.001 | DPT_Colour_RGB 232.600    |
RGBW       | DPT_Scaling 5.001 | DPT_Colour_RGBW 251.600 * |
RGBCW      | DPT_Scaling 5.001 | not supported  +          |

* the validity bits are not supported. Tasmota expect all 4 values R, G, B, W to be present
+ those are not supported because I haven't found a matching DPT for 2 and 5 channels. If someone find one, I can add them later.

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.6
• The code change is tested and works with Tasmota core ESP32 V.3.0.0
• I accept the CLA.

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