Warn about unknown fields when editing settings json (#33678)

Closes #30017

* While generating the settings JSON schema, defaults all schema
definitions to reject unknown fields via `additionalProperties: false`.

* Uses `unevaluatedProperties: false` at the top level to check fields
that remain after the settings field names + release stage override
field names.

* Changes json schema version from `draft07` to `draft_2019_09` to have
support for `unevaluatedProperties`.

Release Notes:

- Added warnings for unknown fields when editing `settings.json`.

crates/call/src/call_settings.rs

@@ -12,7 +12,6 @@ pub struct CallSettings {
 
 /// Configuration of voice calls in Zed.
 #[derive(Clone, Default, Serialize, Deserialize, JsonSchema, Debug)]
-#[schemars(deny_unknown_fields)]
 pub struct CallSettingsContent {
     /// Whether the microphone should be muted when joining a channel or a call.
     ///