python: Support nested analysis settings for Pyright and basedpyright (#62673)

# Objective

Closes #62624

Recently, Pyright and BasedPyright changed how they retrieve analysis
settings through `workspace/configuration` in microsoft/pyright#11480
and DetachHead/basedpyright#1847, respectively. Older versions requested
the dotted `python.analysis` and `basedpyright.analysis` sections
directly. Recent versions instead request the parent `python` or
`basedpyright` section and read its nested `analysis` object. Because
Zed stores many existing configurations under the dotted top-level keys,
those settings are not included in its responses to the new
parent-section requests and are therefore silently ignored.

Zed's documentation and many users' settings still use configurations
like this:

https://github.com/zed-industries/zed/blob/4155155572601034cec5e5cfa9805bf88957553c/docs/src/languages/python.md?plain=1#L131-L148
all the configrations in `basedpyright.analysis` won't work now.

## Solution

To maintain compatibility with both old and new servers, we need to
support both configuration formats. This PR introduces
`normalize_pyright_analysis_configuration`, which copies the analysis
settings into both the dotted and nested formats. This ensures that the
settings are available regardless of which format the language server
requests.

The documentation, however, has been updated to use the nested
structure.

## Testing

New unit tests have been added, and the changes have also been built and
tested locally.

## Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

---

Release Notes:

- Fixed some Pyright and BasedPyright settings not being applied
properly.

docs/src/languages/python.md

@@ -135,10 +135,12 @@ You can use the following configuration:
   "lsp": {
     "basedpyright": {
       "settings": {
-        "basedpyright.analysis": {
-          "diagnosticMode": "workspace",
-          "inlayHints": {
-            "callArgumentNames": false
+        "basedpyright": {
+          "analysis": {
+            "diagnosticMode": "workspace",
+            "inlayHints": {
+              "callArgumentNames": false
+            }
           }
         }
       }
@@ -147,6 +149,8 @@ You can use the following configuration:
 }
 ```
 
+For compatibility with older configurations, Zed also accepts `basedpyright.analysis` as a top-level key within `settings`.
+
 ##### Configuration files
 
 basedpyright reads project-specific configuration from the `pyrightconfig.json` configuration file and from the `[tool.basedpyright]` and `[tool.pyright]` sections of `pyproject.toml` manifests. `pyrightconfig.json` overrides `pyproject.toml` if configuration is present in both places.