Allow users to configure ESLint codeActionOnSave settings (#8537)

This fixes #8533 by allowing users to specify the settings that are
passed to ESLint on workspace initialization.

Example Zed `settings.json` to enable `fixAll` for eslint when
saving/formatting, but only for the `import/order` rule:

```json
{
  "languages": {
    "JavaScript": {
      "code_actions_on_format": {
        "source.fixAll.eslint": true
      }
    }
  },
  "lsp": {
    "eslint": {
      "settings": {
        "codeActionOnSave": {
          "rules": ["import/order"]
        }
      }
    },
  }
}
```

The possible settings are described in the README of `vscode-eslint`
here:
https://github.com/Microsoft/vscode-eslint?tab=readme-ov-file#settings-options

- `eslint.codeActionsOnSave.enable` (default: `true`, config key in Zed:
`lsp.eslint.settings.codeActionOnSave.enable`)
- `eslint.codeActionsOnSave.mode` (default: not set by Zed, config key
in Zed: `lsp.eslint.settings.codeActionOnSave.mode`)
- `eslint.codeActionsOnSave.rules` (default: `[]`, config key in Zed:
`lsp.eslint.settings.codeActionOnSave.rules`)

Yes, in the readme it's plural: `codeActionsOnSave`, but since
`eslint-vscode` we're using this old release:


https://github.com/microsoft/vscode-eslint/releases/tag/release%2F2.2.20-Insider

We use the singular version:
https://github.com/microsoft/vscode-eslint/blob/release/2.2.20-Insider/server/src/eslintServer.ts#L461

Our schema looks like this:

```json
{
  "lsp": {
    "eslint": {
      "settings": {
        "codeActionOnSave": {
          "enable": true,
          "rules": ["import/order"],
          "mode": "all"
        }
      }
    },
  }
}
```

We should probably fix this and upgrade to the newest version of ESLint.

Release Notes:

- Added ability for users to configure settings for ESLint's
`codeActionOnSave`, e.g. specifying `rules` that should be respected
when also using `"code_actions_on_format": {"source.fixAll.eslint":
true}`. These settings can be passed to ESLint as part of the `"lsp"`
part of the Zed settings. Example: `{"lsp": {"eslint": {"settings":
{"codeActionOnSave": { "rules": ["import/order"] }}}}}`
([#8533](https://github.com/zed-industries/zed/issues/8533)).

Demo:


https://github.com/zed-industries/zed/assets/1185253/5c0cf900-9acb-4a70-b89d-49b6eeb6f0e4

crates/project_core/src/project_settings.rs

@@ -64,6 +64,7 @@ pub enum GitGutterSetting {
 #[serde(rename_all = "snake_case")]
 pub struct LspSettings {
     pub initialization_options: Option<serde_json::Value>,
+    pub settings: Option<serde_json::Value>,
 }
 
 impl Settings for ProjectSettings {