Add title feature to notify entity platform

[jbouwh]

Proposed change

Add title feature to notify entity platform.

Architecture discussion: home-assistant/architecture#1041
Developer docs PR: home-assistant/developers.home-assistant#2163
User docs PR: home-assistant/home-assistant.io#32576

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• 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: Add title option to notify entity home-assistant.io#32576 Add title param to notify send_message service - add blog post developers.home-assistant#2163

Checklist

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

If user exposed functionality or configuration variables are added/changed:

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

If the code communicates with devices, web services, or third-party tools:

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  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• For the updated dependencies - a link to the changelog, or at minimum a diff between library versions is added to the PR description.
• Untested files have been added to .coveragerc.

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[home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as it has been labeled with an integration (notify) you are listed as a code owner for? Thanks!

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[MartinHjelmare]

Please link to the architecture discussion.

[jbouwh]

Please link to the architecture discussion.

Done. Also linked docs PR and dev docs PR (including blog post update).

[home-assistant]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

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[jbouwh]

Thanks!