Debounce refresh of inlay hints on buffer edits (#8282)

I think this makes it less chaotic to edit text when the inlay hints are
on.

It's for cases where you're editing to the right side of an inlay hint.
Example:

```rust
for name in names.iter().map(|item| item.len()) {
    println!("{:?}", name);
}
```

We display a `usize` inlay hint right next to `name`.

But as soon as you remove that `.` in `names.iter` your cursor jumps
around because the inlay hint has been removed.

With this change we now have a 700ms debounce before we update the inlay
hints.

VS Code seems to have an even longer debounce, I think somewhere around
~1s.

Release Notes:

- Added debouncing to make it easier to edit text when inlay hints are
enabled and to save rendering of inlay hints when scrolling. Both
debounce durations can be configured with `{"inlay_hints":
{"edit_debounce_ms": 700}}` (default) and `{"inlay_hints":
{"scroll_debounce_ms": 50}}`. Set a value to `0` to turn off the
debouncing.


### Before


https://github.com/zed-industries/zed/assets/1185253/3afbe548-dcfb-45a3-ab9f-cce14c04a148



### After



https://github.com/zed-industries/zed/assets/1185253/7ea90e42-bca6-4f6c-995e-83324669ab43

---------

Co-authored-by: Kirill <kirill@zed.dev>

crates/collab/src/tests/editor_tests.rs

@@ -1426,6 +1426,8 @@ async fn test_mutual_editor_inlay_hint_cache_update(
             store.update_user_settings::<AllLanguageSettings>(cx, |settings| {
                 settings.defaults.inlay_hints = Some(InlayHintSettings {
                     enabled: true,
+                    edit_debounce_ms: 0,
+                    scroll_debounce_ms: 0,
                     show_type_hints: true,
                     show_parameter_hints: false,
                     show_other_hints: true,
@@ -1438,6 +1440,8 @@ async fn test_mutual_editor_inlay_hint_cache_update(
             store.update_user_settings::<AllLanguageSettings>(cx, |settings| {
                 settings.defaults.inlay_hints = Some(InlayHintSettings {
                     enabled: true,
+                    edit_debounce_ms: 0,
+                    scroll_debounce_ms: 0,
                     show_type_hints: true,
                     show_parameter_hints: false,
                     show_other_hints: true,
@@ -1695,6 +1699,8 @@ async fn test_inlay_hint_refresh_is_forwarded(
             store.update_user_settings::<AllLanguageSettings>(cx, |settings| {
                 settings.defaults.inlay_hints = Some(InlayHintSettings {
                     enabled: false,
+                    edit_debounce_ms: 0,
+                    scroll_debounce_ms: 0,
                     show_type_hints: false,
                     show_parameter_hints: false,
                     show_other_hints: false,
@@ -1707,6 +1713,8 @@ async fn test_inlay_hint_refresh_is_forwarded(
             store.update_user_settings::<AllLanguageSettings>(cx, |settings| {
                 settings.defaults.inlay_hints = Some(InlayHintSettings {
                     enabled: true,
+                    edit_debounce_ms: 0,
+                    scroll_debounce_ms: 0,
                     show_type_hints: true,
                     show_parameter_hints: true,
                     show_other_hints: true,