Security settings: Add "Complete security" button

[manuroe]

Display it when cross-signing is up on the account but

• our device does not trust it
• or our device does not have private keys

This needs to be done after #3003 as it will reuse some parts of it.

• Need to Check RiotX-Android first

We need it on:

• Settings > Security > MY SESSIONS (done in BF: Settings - Security: My device is not trusted #3145)
• Settings > Security > CROSS-SIGNING
• Room member screen for my self (Cross-signing: Self verification in a room use DM request instead of to_device #3108)