Bumps `gutter_padding_factor` from 3.5 to 4.0 due git mark on the gutter
becoming much thicker than in Zed1:
 
Current:

![current_zed_2](https://github.com/zed-industries/zed/assets/2690773/f7f0f76b-63a2-4790-a4f4-ca791b617a64)

Fixed:

![new_zed2](https://github.com/zed-industries/zed/assets/2690773/0075567d-e661-4140-8ffa-ec17d72f8e54)

Stable (no hover background appearing):

![zed_1](https://github.com/zed-industries/zed/assets/2690773/c3366845-b763-46f7-a2c7-48dd72dc4f10)

Release Notes:

- Fixed gutter marks overlapping with hover highlights

NextMatch/PreviousMatch did not work due to us not updating the match index in the buffer search (that relied on an event being emitted).

Fixes https://github.com/zed-industries/community/issues/2426

Release Notes:

- Fixed a bug that was preventing diagnostics from being shown on hover.

With this pull request, we're introducing a `ZED_MEASUREMENTS` variable
which is used by the `measure` function to print to stderr how long it
took to execute a given closure. This is used right now to measure frame
time when a new frame is requested. This data can be plotted as a
histogram via `script/histogram`.

Here's a workflow I typically use:

- Run `export ZED_MEASUREMENTS=1`
- Checkout a commit that you want to measure the performance of
- Run zed in release mode and use it for 5-10 seconds
- Copy the printed measurements into a file, say `version-a`
- Checkout another commit that you want to measure the performance of
- Run zed in release mode and use it for 5-10 seconds
- Copy the printed measurements into a file, say `version-b`
- Run `script/histogram version-a version-b` (note that you can supply
however many files you want)

Release Notes:

- N/A

I'm sure @iamnbutler can do a better job here, this is just hacky, but
the size of the icon when doing `Cmd+tab` has been bugging me, so I
thought I'd resize them quickly to the dimensions the Stable/Preview
icons have.

Release Notes:

- N/A

During the doc parties, I've sometimes struggled with how and where to
describe the high level intention behind various APIs that are available
in GPUI. Fortunately, rust doc has a tool for this: Module level
documentation. However, writing this kind of documentation for the
`WindowContext` is difficult, as it bundles up the nice, high level GPUI
APIs for entity management and view rendering, with all of the low level
imperative APIs that `Element`s use to draw to the screen. Splitting
these apart into an `ElementContext`, which contains a `WindowContext`,
gives us a way to corral the element systems into their own API and
module, allowing us to document the Element system on it's own terms,
and enforce the correct usage of our APIs, and helps people who are
exploring our APIs through autocomplete to not be overloaded with
non-applicable methods.

Release Notes:

- N/A

Before this change if you had a matching binding and a pending key,
the matching binding happened unconditionally.

Now we will wait a second before triggering that binding to give you
time to complete the action.

Also add several `TODO!(docs)` comments to places that need more
feedback.

Release Notes:

- N/A

<img width="447" alt="SCR-20240121-ofhg"
src="https://github.com/zed-industries/zed/assets/19867440/7fe13a74-45c7-43ec-a5e8-5127bc285b32">

In this screenshot, the first two messages were sent back-to-back, but
the third message was sent nearly two hours later. Coalescing the
messages doesn't feel right after a certain period of time, as it gives
misleading timestamps on messages. Discord has this feature, but I'm not
sure what the value they use is. I've set the threshold to 5 minutes for
now.

<img width="480" alt="SCR-20240121-oghs"
src="https://github.com/zed-industries/zed/assets/19867440/ee1cfe36-7c13-4072-9f66-93e2de6542f1">

Release Notes:

- Improved the grouping of chat messages from same user. Grouping now
only occurs if the user sends multiple messages, in succession, within a
specified duration of time.

A user was not seeing the "yesterday" text in their chat timestamps for
messages right before the midnight boundary

Release Notes:

- Fixed bugs in formatting of chat timestamps

This matches Neovim behaviour by setting the mode to `Normal` when using
search while in visual mode.

Release Notes:

- Fixed Vim mode not switching to normal mode from visual mode when
using search (`/`) while in visual mode.

This doesn't cover everything that should be tested in telemetry, but it
is a start. I'll add more over time.

Release Notes:

- N/A

That took a while.

I also removed an instance of SmallVec leaking into the public GPUI
APIs.

Release Notes:

- N/A

Remove SmallVec from the public API of GPUI

Release Notes:

- Channels: Improved font sizes in chat
- Channels: Added a link preview when hovering over links in chat
- Channels: Fixed rendering of newlines in chat messages
- Added a new setting "use_autoclose" (defaulting to true) that lets you
disable autoclose per language.
([#1420](https://github.com/zed-industries/community/issues/1420))
([#1903](https://github.com/zed-industries/community/issues/1903))

In the process I also:
- Made the AsyncWindowContext slightly more ergonomic.
- Refactored the input handler traits to enable easy, non-view input
handlers
- Locked down the visibility on all mac-specific GPUI code
- Documented all remaining, public types

Release Notes:

- N/A

Add documentation to all platform types

Also disable autoclose for Chat