Add limited templates to time trigger at option

[Petro31]

Proposed change

Add the ability to use limited templates for the at field on time triggers. This will allow blueprint creators to use input fields in limited templates and piece together times and or entity_id's that satisfy the at field.

e.g.

trigger_variables:
  my_entity: !input my_entity
  my_time: !input my_time
trigger:
- platform: time
  at: "{{ my_entity if my_entity is not none else my_time }}"

Type of change

• [ ] Dependency upgrade
• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New integration (thank you!)
• [x] New feature (which adds functionality to an existing integration)
• [ ] Deprecation (breaking change to happen in the future)
• [ ] Breaking change (fix/feature causing existing functionality to break)
• [ ] Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request: https://github.com/home-assistant/home-assistant.io/pull/33624

Checklist

• [x] The code change is tested and works locally.
• [x] Local tests pass. Your PR cannot be merged unless tests pass
• [x] There is no commented out code in this PR.
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• [x] I have followed the perfect PR recommendations
• [x] The code has been formatted using Ruff (ruff format homeassistant tests)
• [x] Tests have been added to verify that the new code works.

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• [x] Documentation added/updated for www.home-assistant.io

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