Delete till previous tabstop when backspacing within indent column

Eliminate ToFoldPoint trait

Just make it a method on FoldMap

Co-Authored-By: Keith Simmons <keith@zed.dev>

Reset receive timeout only on reads from the websocket connection, not writes

Also, increase the receive timeout to 30 seconds. We'll still respond immediately
to explicit disconnection, but when there are temporary network blips that
delay pings, we think we should err on the side of keeping the connection
alive. This is in response to a false positive 'host disconnected' state
that we observed when pairing today, while the host (Keith) still clearly
had a working internet connection, because we were screen sharing.

Co-Authored-By: Keith Simmons <keith@zed.dev>

Make theme selector eagerly display the selected theme

Refine bracket auto-closing behavior

Notify all language servers when a buffer gets saved

This gives clients a chance to register to notifications.

We added this because we thought it would save some allocations when
sending operations given that we could move them to the delegate upon
notifying it, but the reality is that we serialize operations and that
only requires a reference.

Other notifications such as opening, closing or changing a document
are still tied to the buffer's language.

Also, make LanguageServer::new() async. The future resolves
once the server is initialized.

Co-Authored-By: Max Brunsfeld
Co-Authored-By: Nathan Sobo

Co-Authored-By: Nathan Sobo <nathan@zed.dev>
Co-Authored-By: Antonio Scandurra <antonio@zed.dev>
Co-Authored-By: Keith Simmons <keith@zed.dev>

Populate environment from shell

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

Send heartbeats in both directions so the server can detect when clients disconnect

* Make advance_clock more realistic by waking timers in order,
  instead of all at once.
* Don't advance the clock when simulating random delays.

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

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

Halt keystroke dispatch when a global action is dispatched

Ensure `active_item_index` doesn't go off the end when closing items

This fixes a bug introduced in #538, where closing the current tab would hide
all the other tabs, if the current tab was the last one.

Also, this commit manually sets the active item index instead of calling
`Pane::activate_item`: even though this introduces a little bit of duplication,
it prevents us from mistakenly calling `deactivate` on the wrong item. This would
happen because `activate_item` looks at `self.active_item_index` to determine
which item to deactivate before setting the new one. However, that index is
potentially invalid because `::close_items` manipulates the `item_views` vector,
so `activate_item` could end up calling `deactivate` on an item view that was
not active in the first place.

Implement close inactive items

When a network connection is lost without being explicitly closed by the
other end, writes to that connection will error, but reads will just wait
indefinitely.

This allows the tests to exercise our heartbeat logic.