Remember microphone mute state when rejoining a call

[jancborchardt]

Fix #4938

Currently joining a call will always enable your microphone again, even if you muted it beforehand.
On mobile it’s quite likely that you are in a noisy environment you want to mute yourself in. So now that state is globally remembered, also similar to other apps (except WhatsApp & Signal which are more "phone call" like rather than conference calls).

This also works fine for 1on1 calls, cause there you are likely not muted. Last setting is remembered, which means you will not be muted on reconnect either.

🖼️ Screenshots

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• ⛑️ Tests (unit and/or integration) are included or not needed
• 🔖 Capability is checked or not needed
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[github-actions]

APK file: https://github.com/nextcloud/talk-android/actions/runs/28812951039/artifacts/8118067498
To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.
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