chore: introduce platform object for platform specific code

packages/hoppscotch-common/src/index.ts

@@ -1,4 +1,4 @@
-import { createApp } from "vue"
+import { createApp, Ref } from "vue"
 import { setupLocalPersistence } from "./newstore/localpersistence"
 import { performMigrations } from "./helpers/migrations"
 import { initializeFirebase } from "./helpers/fb"
@@ -12,7 +12,26 @@ import "nprogress/nprogress.css"
 
 import App from "./App.vue"
 
-export function createHoppApp(el: string | Element) {
+export type PlatformDef = {
+  ui?: {
+    appHeader?: {
+      paddingTop?: Ref<string>
+      paddingLeft?: Ref<string>
+    }
+  }
+}
+
+/**
+ * Defines the fields, functions and properties that will be
+ * filled in by the individual platforms.
+ *
+ * This value is populated upon calling `createHoppApp`
+ */
+export let platform: PlatformDef
+
+export function createHoppApp(el: string | Element, platformDef: PlatformDef) {
+  platform = platformDef
+
   const app = createApp(App)
 
   // Some basic work that needs to be done before module inits even