Add initial inline diagnostics support (#25297)

https://github.com/user-attachments/assets/eb881707-e575-47ef-9ae0-67d8085d8065

Closes https://github.com/zed-industries/zed/pull/22668
Closes https://github.com/zed-industries/zed/issues/4901

Takes https://github.com/zed-industries/zed/pull/22668 and fixes all
review items on top.
Inline diagnostics are disabled by default, but can be enabled via
settings permanently, or temporarily toggled with the `editor:
ToggleInlineDiagnostics` action and the corresponding editor menu item
<img width="242" alt="image"
src="https://github.com/user-attachments/assets/8e177511-4626-4434-902b-d6aa4d3fafd0"
/>

Inline diagnostics does not show currently active diagnostics group, as
it gets inline into the editor too, inside the text.
Inline git blame takes precedence and is shown instead of the
diagnostics, edit predictions dim the diagnostics if located on the same
line.

One notable drawback of the implementation is the inability to wrap,
making inline diagnostics cut off the right side:


![image](https://github.com/user-attachments/assets/6e87268a-b51a-4a2b-8b8d-01d932c62fea)

(same as inline git blame and other elements to the right of the text)
Given that it's disabled by default and go to next/prev diagnostics will
show them better, seems fine to leave in the first iteration.


Release Notes:

- Added initial inline diagnostics support

---------

Co-authored-by: Paul J. Davis <paul.davis@tiledb.com>
Co-authored-by: Danilo Leal <daniloleal09@gmail.com>

assets/settings/default.json

@@ -760,7 +760,25 @@
   // Diagnostics configuration.
   "diagnostics": {
     // Whether to show warnings or not by default.
-    "include_warnings": true
+    "include_warnings": true,
+    // Settings for inline diagnostics
+    "inline": {
+      // Whether to show diagnostics inline or not
+      "enabled": false,
+      // The delay in milliseconds to show inline diagnostics after the
+      // last diagnostic update.
+      "update_debounce_ms": 150,
+      // The amount of padding between the end of the source line and the start
+      // of the inline diagnostic in units of em widths.
+      "padding": 4,
+      // The minimum column to display inline diagnostics. This setting can be
+      // used to horizontally align inline diagnostics at some column. Lines
+      // longer than this value will still push diagnostics further to the right.
+      "min_column": 0,
+      // The minimum severity of the diagnostics to show inline.
+      // Shows all diagnostics when not specified.
+      "max_severity": null
+    }
   },
   // Files or globs of files that will be excluded by Zed entirely. They will be skipped during file
   // scans, file searches, and not be displayed in the project file tree. Takes precedence over `file_scan_inclusions`.