Support preset modes and percentage for mqtt fan

[jbouwh]

Proposed change

The fan entity model has changed. The code and documentation has updated to support fan speed percentage and preset mode functions. Using legacy speeds is deprecated.

Type of change

• Spelling, grammar or other readability improvements (current branch).
• Adjusted missing or incorrect information in the current documentation (current branch).
• Added documentation for a new integration I'm adding to Home Assistant (next branch).
  • I've opened up a PR to add logo's and icons in Brands repository.
• Added documentation for a new feature I'm adding to Home Assistant (next branch).
• Removed stale or deprecated documentation.

Additional information

• Link to parent pull request in the codebase: (Percentage and preset mode support for MQTT fan core#47944)
• Link to parent pull request in the Brands repository:
• This PR fixes or closes issue:

Checklist

• This PR uses the correct branch, based on one of the following:
  • I made a change to the existing documentation and used the current branch.
  • I made a change that is related to an upcoming version of Home Assistant and used the next branch.
• The documentation follows the Home Assistant documentation standards.

[jbouwh]

One abbreviation 'pr_mode_value_tpl' should be corrected,

[emontnemery]

Looks good!

[emontnemery]

There was a mistake here, this should have targetted next branch, not current (core PR is not in 2021.3, but will be in 2021.4).

[frenck]

Will adjust this manually

[frenck]

Done, it has been reverted on current and is now re-applied on next.