Fix IME regressions

They regressed as part of https://github.com/zed-industries/zed/pull/1405.

Fixed regression in working directory code

Co-authored-by: Keith Simmons <keith@zed.dev>

Rebalance text and icon color usage...

...to better differentiate between primary, secondary and muted.

Fix tab bar themes

Update arrow variants, download, check marks to use Font awesome icon variants

Improve sorting of project symbols and completions

Clip invalid edits from LSP instead of reporting an error

This fixes an issue with the Go language server, which reports invalid
formatting ranges when there's a missing newline at the end of the file.
Specifically, if the buffer is `N` lines long, it will try to insert the
newline at `Point(N + 1, 0)`.

I confirmed the behavior is the same in VS Code, and they indeed clip the
LSP ranges as well.

Log instead of showing an alert when exiting due to no GPU

Fixed keybinding regression

Showing the alert resulted in a panic because tasks
dispatched to the app's main GCD queue continue
to run even while the alert is displayed.

Allow closing tabs with the middle mouse button

Improve support for non-US keyboards and input

Now, instead of using these versioned offset ranges, we locate the
fragments associated with a transaction using the transaction's
edit ids. To make this possible, buffers now store a new map called
`insertion_slices`, which lets you look up the ranges of insertions
that were affected by a given edit.

Co-authored-by: Antonio Scandurra <antonio@zed.dev>

Polishing the terminal