feat: mark saved messages chat as protected

[link2xt]

Fixes #4561

[link2xt]

Needs test fixes.

[r10s]

makes sense to me.

i first also thought "what about unencrypted from SELF", but following the exceptions @Hocuri clarified wrt outgoing mails at #4561 (comment) it seems fine, +1

after merging, let's see if all UI really show the green checkmark - saved-messages and device-chats are special in some regards :)

[link2xt]

Another option would be to just stamp a green checkmark on Saved messages in the UI :)

[link2xt]

test_webxdc_internet_access is still broken, it tests that in 1:1 chat when you disable E2E it actually get disabled, webxdc is sent unencrypted and gets no internet access.

Unintended consequence of protecting 1:1 chat is that it is now impossible to disable E2E even if you switch the setting off.

Should we:

1. Send unencrypted messages to saved messages chat with a green checkmark if user disabled E2EE?
2. Say that it is impossible to disable E2EE in saved messages chat?
3. Do not mark saved messages chat with a green checkmark after all?

[iequidoo]

Unintended consequence of protecting 1:1 chat is that it is now impossible to disable E2E even if you switch the setting off.

But it's the problem for all 1:1-s, not only for the saved messages' chat, right?

off-topic

Sorry, but i still think that [the only] 1:1 chat is just a misconcept came from other messengers. It should be a usual 2-member group, protected or not, maybe also with protection from adding extra members. Then you can disable e2ee and create another chat.

Send unencrypted messages to saved messages chat with a green checkmark if user disabled E2EE?

Probably a solution, but then the green checkmark shouldn't be shown.

[Hocuri]

+1 for the solution "if user disabled E2EE, then send messages unencrypted and don't show the green checkmark". Not a priority though, I think for now it's fine to just not mark the saved messages chat as protected, and leave things as they are.