Use 16-bit float to store path windings

Previously, we were using a normalized 8-bit unsigned integer which forced us
to represent each increment of the winding number as a fraction of the max
value (1 / 255) which we would then add up using additive alpha blending.

This had three major drawbacks:

- The max winding number could not be greater than 255.
- Adding up (1 / 255) several times could result in a loss of precision.
- Due to also computing anti-aliasing as a fractional winding number, we had to
  reduce the max winding number to 32. This was still not good enough because
  we would multiply a fractional value with `1 / 32`, thus introducing more and
  more loss of precision.

This commit changes the texture type to an `f16` which doesn't require the
division by 255 and enables greater precision in the computation of the
anti-aliased parts of a curve. Note how this also removes the limitation of 255
windings at most per curve. The tradeoff is paying twice as much memory for
storing the texture, but that seems totally valid to achieve rendering accuracy.

Note that this kind of texture should be compatible with WebGL2 once we start
working on a web version of Zed.

We'll need to detect edits on the child buffers and understand their impact on the tree.

Here I'm exploring a new approach to the project-wide diagnostics view that can exactly mirror the contents of cargo check. The `FragmentList` composes an arbitrary list of fragments from other buffers and presents them as if they were a single buffer.

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Render blocks as arbitrary elements

Co-Authored-By: Max Brunsfeld <maxbrunsfeld@gmail.com>

Co-Authored-By: Max Brunsfeld <maxbrunsfeld@gmail.com>

Co-Authored-By: Max Brunsfeld <maxbrunsfeld@gmail.com>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Don't rely on `Buffer::edits_since` to keep `FoldMap` up-to-date

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Use `&'a Snapshot` directly instead of `impl Into<Content<'a>>`

The text::Buffer and its snapshot already used the same representation
for their content, so we can just make Buffer deref to a Snapshot.

Improve file navigation by naming the root of every crate after the crate itself

Co-Authored-By: Max Brunsfeld <maxbrunsfeld@gmail.com>

Co-Authored-By: Max Brunsfeld <maxbrunsfeld@gmail.com>

Co-Authored-By: Max Brunsfeld <maxbrunsfeld@gmail.com>

Avoid building up pending edits when soft wrapping is disabled

This was causing us to get slower over time as we stacked up hundreds of thousands of pending edits whenever soft wrap was disabled.

Co-Authored-By: Antonio Scandurra <me@as-cii.com>

Use display coordinates for the highlighted row in "go to line"

Fix flaky contacts test

We perform an async fetch of client_b's user data on worktree_a, which ends up holding a handle that prevents worktree_a from being released later in the test. By waiting for this fetch to finish before proceeding, we can be sure worktree_a actually gets released.

A more comprehensive fix would be some way to ensure we actually perform a release if an entity is fully dropped outside of an update cycle, but this fixes the issue for now.

Co-Authored-By: Max Brunsfeld <max@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Paint highlighted lines correctly when horizontally scrolled

Override soft-wrap settings for Markdown and Plain Text

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

Show collaborators for the active worktree in the titlebar