#5599 Add checks if rich-text option is enabled before removing support

[martgil]

This PR adds check ensuring that rich-text is enable before ever removing rich text formatting. This solves the issue of having a prepended newlines when typing, for example, "HelloEnterWorld" where it produces

World
Hello

in the contenteditable.div in the master branch.

To test this manually:

1.) Open Gmail with FlowCrypt browser extension installed and configured.
2.) Send you're self a signed message email.
3.) Reply to your own signed message email. (The bug appears at this point on "master" branch but not here.)
4.) Type "HelloEnterWorld" and it will produce output on contenteditable.div correctly with:

Hello
World

instead of the bugged version:

World
Hello

close #5599

---

Tests (delete all except exactly one):

• Difficult to test (explain why) - It's difficult to test it in automated manners for some reason as I get correct output's when doing testing for both master and this branch. So looks like the bug is particularly be reproducible through actual usage. I can share this build to the reporting users for them to double check it -- though it works perfectly when i tested it.

---

To be filled by reviewers

I have reviewed that this PR... (tick whichever items you personally focused on during this review):

• addresses the issue it closes (if any)
• code is readable and understandable
• is accompanied with tests, or tests are not needed
• is free of vulnerabilities
• is documented clearly and usefully, or doesn't need documentation

[martgil]

Hello @sosnovsky - may I hear your feedback regarding this whenever your are available. Once confirmed that this looks good to you, I'll be sharing a custom build to the reporting users for them to see it working on their side before we can merge this. Thanks!

[sosnovsky]

Hi @martgil - I tried to reproduce mentioned bug on master build, but everything worked well for me.
Maybe you can share video of this issue by email?
You can also share this build with reporting users, to check if provided fix works for them.

[martgil]

Yes, Roma - I just sent a screencast over secure email. Thanks!

[martgil]

I will also create a custom build now and share to the reporting users.

[sosnovsky]

I was able to reproduce original issue, and your fix works well 👍