desktop: fix big input, and other desktop web issues

[patosullivan]

fixes TLON-3273 (making the BigInput actually usable on desktop) We weren't accounting for big input height.

Also fixes other issues:

Notebooks weren't wrapped in a Pressable.

Some bad conditional checks were causing text strings to render outside of Text components/directly within Stack components.

Edits weren't working at all for notebook posts (we weren't filling in the draft content, we weren't passing along the title, and we weren't handling situations where the post had an image).

We were still unnecessarily using a ScrollView for the web version of the BigInput.

We had no way to allow the user to exit the big input editor if they wanted to abandon creating a post.

We were attempting to pass contentFit as a prop to img tags for web, which isn't a valid attribute, which made the image header in the notebook editor too large. I added a way to catch contentFit and pass it to the img as an objectFit property in the style prop. This also fixes an issue where image avatars weren't displaying correctly much of the time.

We had no overflow menu button on notebook posts, so there was no way to get to the message options on desktop.

General cleanup of the web MessageInput component.

Edit: now also adds an overflow button for gallery posts.

[linear]

TLON-3273 Should be able to add/edit notes and text gallery posts

[latter-bolden]

Looks good, didn't see any regressions checking against native.

Only UX thing that threw me off was clicking into an empty big input didn't focus it unless I hit within the height of the first line.

[dnbrwstr]

Couple comments