- opens as a modal
- lastn is 0, mutes local video while open
- long press to talk
- and more

Only havee the screen in the hierarchy if we have a welcome page, since
it's the only way to access it.

Use goBack() from the navigator directly and avoid duplicating all props
to the screen.

It allows us to place the Cancel button there, and declutter the UI of
buttons.

Skip the welcome page for now, until we can remove the audio / video
toggle.

Update Android build to support gif
Use GIF format instead of animated webp
Show GIFs in chat messages
Display GIF over tile
Add Giphy button in reactions menu
Added Giphy dialog
Fix isGifMessage to also allow upper case

Updated screens with new ui on mobile

React Navigation v6.

* feat(security) Security Options screen

Introduce navigation for all in-conference screens.