Add service ota_update to shelly integration

[mib1185]

Proposed change

This PR adds a new service ota_update to the shelly integration, which is intended to trigger OTA updates to a single or multiple devices at the same time.

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: Add service ota_update to shelly integration core#48448
• 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.

[frenck]

This was the indication for me to go to the parent PR and leave a comment on the implementation. This should be implemented as an entity service.

That way, it can use a target (meaning, entity_id, area_id or device_id and even a mix of it, is accepted).