Add basic media query auto complete support (#443)

* Add basic media query auto complete support

* build

* Status support

* Add `: ` and trigger suggestion

* Add test

* Only suggest value if not on feature name

* Add schema

* MediaQuery is not a BodyDeclaration

---------

Co-authored-by: Martin Aeschlimann <martinae@microsoft.com>

Author: Legend-Master

docs/customData.schema.json

@@ -37,6 +37,38 @@
           "description": "Description shown in completion and hover"
         }
       }
+    },
+    "descriptor": {
+      "type": "object",
+      "required": ["name"],
+      "properties": {
+        "name": {
+          "type": "string",
+          "description": "The name of the descriptor."
+        },
+        "description": {
+          "description": "Description of at descriptor shown in completion and hover",
+          "anyOf": [
+            {
+              "type": "string"
+            },
+            { "$ref": "#/definitions/markupDescription" }
+          ]
+        },
+        "status": {
+          "$ref": "#/properties/properties/items/properties/status"
+        },
+        "browsers": {
+          "$ref": "#/properties/properties/items/properties/browsers"
+        },
+        "references": {
+          "type": "array",
+          "description": "A list of references for the descriptor shown in completion and hover",
+          "items": {
+            "$ref": "#/definitions/references"
+          }
+        }
+      }
     }
   },
   "properties": {
@@ -168,6 +200,13 @@
             "items": {
               "$ref": "#/definitions/references"
             }
+          },
+          "descriptors": {
+            "type": "array",
+            "description": "A list of descriptors for the at-directive, for example prefers-reduced-motion for @media",
+            "items": {
+              "$ref": "#/definitions/descriptor"
+            }
           }
         }
       }

src/cssLanguageTypes.ts

@@ -198,13 +198,25 @@ export interface IPropertyData {
 	relevance?: number;
 	atRule?: string;
 }
+export interface IDescriptorData {
+	name: string,
+	description?: string,
+	references?: IReference[],
+	syntax?: string,
+	type?: string,
+	values?: IValueData[]
+	browsers?: string[];
+	baseline?: BaselineStatus;
+	status?: EntryStatus;
+}
 export interface IAtDirectiveData {
 	name: string;
 	description?: string | MarkupContent;
 	browsers?: string[];
 	baseline?: BaselineStatus;
 	status?: EntryStatus;
 	references?: IReference[];
+	descriptors?: IDescriptorData[];
 }
 export interface IPseudoClassData {
 	name: string;