[json-language-features] Fix json/schemaAssociations parameters documentation

The `json/schemaAssociations` documentation is not accurate in stating
that the only supported parameter is an object in `{ pattern: uri }`
format. It also supports the structure defined by `SchemaConfiguration`
interface from "vscode-json-languageservice".

Also updated the server code to match that.

Resolves #106060

extensions/json-language-features/server/README.md

@@ -143,15 +143,34 @@ In addition to the settings, schemas associations can also be provided through a
 
 Notification:
 - method: 'json/schemaAssociations'
-- params: `ISchemaAssociations` defined as follows
+- params: `ISchemaAssociations | SchemaConfiguration[]` defined as follows
 
 ```ts
-interface ISchemaAssociations {
-	[pattern: string]: string[];
+/**
+ * An object where:
+ *  - keys are file names or file paths (separated by `/`). `*` can be used as a wildcard.
+ *  - values ar an arrays of schema URLs
+ */
+type ISchemaAssociations = Record<string, string[]>
+
+interface SchemaConfiguration {
+    /**
+     * The URI of the schema, which is also the identifier of the schema.
+     */
+    uri: string;
+    /**
+     * A list of file path patterns that are associated to the schema. The '*' wildcard can be used. Exclusion patterns starting with '!'.
+     * For example '*.schema.json', 'package.json', '!foo*.schema.json'.
+     * A match succeeds when there is at least one pattern matching and last matching pattern does not start with '!'.
+     */
+    fileMatch?: string[];
+    /**
+     * The schema for the given URI.
+     * If no schema is provided, the schema will be fetched with the schema request service (if available).
+     */
+    schema?: JSONSchema;
 }
 ```
-  - keys: a file names or file path (separated by `/`). `*` can be used as a wildcard.
-  - values: An array of schema URLs
 
 Notification:
 - method: 'json/schemaContent'