Change Room Card to support knocking

[wizzeh]

Description

Updates the Room Card to support MSC 2403. Cinny allows server admins to set rooms to knock only but doesn't allow users to actually make knocks. This PR is just a simple change to add knocking.

As a side effect we can also notify the user when a server is invite-only. This could be a separate PR if desired but I've wrapped it in here. The current behavior where you hit join and then get an error is confusing.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• [✓] New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• [✓] My code follows the style guidelines of this project
• [✓] I have performed a self-review of my own code
• [✓] I have commented my code, particularly in hard-to-understand areas
• [✓] I have made corresponding changes to the documentation
• [✓] My changes generate no new warnings

[github-actions]

All contributors have signed the CLA ✍️ ✅
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[wizzeh]

I have read the CLA Document and I hereby sign the CLA