Add initial element inspector for Zed development (#31315)

Open inspector with `dev: toggle inspector` from command palette or
`cmd-alt-i` on mac or `ctrl-alt-i` on linux.

https://github.com/user-attachments/assets/54c43034-d40b-414e-ba9b-190bed2e6d2f

* Picking of elements via the mouse, with scroll wheel to inspect
occluded elements.

* Temporary manipulation of the selected element.

* Layout info and JSON-based style manipulation for `Div`.

* Navigation to code that constructed the element.

Big thanks to @as-cii and @maxdeviant for sorting out how to implement
the core of an inspector.

Release Notes:

- N/A

---------

Co-authored-by: Antonio Scandurra <me@as-cii.com>
Co-authored-by: Marshall Bowers <git@maxdeviant.com>
Co-authored-by: Federico Dionisi <code@fdionisi.me>

Cargo.lock

@@ -112,7 +112,6 @@ dependencies = [
  "serde_json",
  "serde_json_lenient",
  "settings",
- "smallvec",
  "smol",
  "streaming_diff",
  "telemetry",
@@ -8159,6 +8158,26 @@ dependencies = [
  "generic-array",
 ]
 
+[[package]]
+name = "inspector_ui"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "command_palette_hooks",
+ "editor",
+ "gpui",
+ "language",
+ "project",
+ "serde_json",
+ "serde_json_lenient",
+ "theme",
+ "ui",
+ "util",
+ "workspace",
+ "workspace-hack",
+ "zed_actions",
+]
+
 [[package]]
 name = "install_cli"
 version = "0.1.0"
@@ -8931,8 +8950,10 @@ dependencies = [
  "regex",
  "rope",
  "rust-embed",
+ "schemars",
  "serde",
  "serde_json",
+ "serde_json_lenient",
  "settings",
  "smol",
  "snippet_provider",
@@ -19750,6 +19771,7 @@ dependencies = [
  "image_viewer",
  "indoc",
  "inline_completion_button",
+ "inspector_ui",
  "install_cli",
  "jj_ui",
  "journal",