Implement custom icons per workspace. (#261)

* Implement custom icons per workspace.

* Finish custom workspace icon implementation

* Remove unsupported color definition.

lib/types/workspace.d.ts

@@ -10,3 +10,16 @@ export type WorkspaceMap = {
 export type MonitorMap = {
     [key: number]: string;
 };
+
+export type WorkspaceIcons = {
+    [key: string]: string;
+};
+
+export type WorkspaceIconsColored = {
+    [key: string]: {
+        color: string;
+        icon: string;
+    };
+};
+
+export type WorkspaceIconMap = WorkspaceIcons | WorkspaceIconsColored;