Co-authored-by: Julia Risley <julia@zed.dev>

- Tighten up toolbar
- Reduce intensity of active tools
- Remove divider between project + branch
- Add a styletree for toolbar + move breadcrumb into it
- Some ts theme tidying

[[PR Description]]

Release Notes:

- Improved density and contrast of a number of UI elements.

![CleanShot 2023-08-28 at 12 24
36@2x](https://github.com/zed-industries/zed/assets/482957/f97cb399-1ac2-4fa9-94a7-137d1eec711c)


Release Notes:

- Added a new "Inline Assist" feature that lets you transform a
selection or generate new code at the cursor location by hitting
`ctrl-enter`.

This only works in-memory for now.

Deals with https://github.com/zed-industries/community/issues/1116
Part of https://github.com/zed-industries/community/issues/1098

Use Mac platform callbacks to send a global event and enable/disable
caret blinking in editors when the app is not focused.

Release Notes:

- Stop blinking caret if Zed app is not focused

Before this change the bounday could mistakenly have happened on a soft
line wrap.

Also fixes interaction with inlays better.

Co-authored-by: Max <max@zed.dev>

This PR polishes the search bar UI, making the layout more dense, and
the spacing more consistent with the rest of the app. I've also
re-ordered the toolbar items to reflect some of @iamnbutler's original
search designs. The items related to the search query are on the left,
and the actions that navigate the buffer (next, prev, select all, result
count) are on the right.

co-authored-by: Max <max@zed.dev>

This changes vim motions to be relative to fold lines, not display
lines, to match the behaviour of vim.

This is necessary for relative line numbers to make sense (as the most
important thing is you can do `3j` to get th e line that is numbered 3).


Release Notes:

- vim: Fix handling of motions when `soft_wrap` is enabled in zed. Like
in vim `j,k,up,down,$,^,0,home,end` will all now navigate in file
coordinates not display coordinates.
- vim: Add `g {j,k,up,down,$,^,0,home,end}` to navigate in display
coordinates.
- vim: Add `z o` and `z c` to open and close folds.
- vim: Add `z f` in visual mode to fold selection.

Note: this may be a jarring change if you're grown used to the current
behaviour of `j` and `k`. You can make the issue less acute by setting
`"soft_wrap":"none"` in your settings; or you can manually copy the
bindings for `g j` to the binding for `j` (etc.) in your keymap.json to
preserve the existing behaviour.

Release Notes:

- Add a `"ctrl-shift-:": "editor::ToggleInlayHints"` default binding

Lately, I've been finding Rust-analyzer unusably slow when editing large
files (like `editor_tests.rs`, or `integration_tests.rs`). When I
profile the Rust-analyzer process, I see that it sometimes saturates up
to 10 cores processing a queue of code actions requests.

Additionally, sometimes when collaborating on large files like these, we
see long delays in propagating buffer operations. I'm still not sure why
this is happening, but whenever I look at the server logs in Datadog, I
see that there are remote `CodeActions` and `DocumentHighlights`
messages being processed that take upwards of 30 seconds. I think what
may be happening is that many such requests are resolving at once, and
the responses are taking up too much of the host's bandwidth.

I think that both of these problems are caused by us sending way too
many code action and document highlight requests to rust-analyzer. This
PR adds a simple debounce between changing selections and making these
requests.

From my local testing, this debounce makes Rust-analyzer *much* more
responsive when moving the cursor around a large file like
`editor_tests.rs`.