[chore/frontend] Refactor status templates slightly, put polls behind CWs if present

[tsmethurst]

Description

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If this is a documentation change, please briefly describe what you've changed and why.

This pull request tidies up our templates a bit:

• Produce more consistently laid out HTML.
• Separate status media attachments into a separate template for readability.
• Put polls inside the CW instead of having them outside (since poll questions can also be sensitive ofc).
• Indicate when a poll is multiple choice.

Closes #2393

Checklist

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• I/we have read the GoToSocial contribution guidelines.
• I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
• I/we have performed a self-review of added code.
• I/we have written code that is legible and maintainable by others.
• I/we have commented the added code, particularly in hard-to-understand areas.
• I/we have made any necessary changes to documentation.
• I/we have added tests that cover new code.
• I/we have run tests and they pass locally with the changes.
• I/we have run go fmt ./... and golangci-lint run.