Screen for searching user's posts (#7622)

* search user's posts screen

* custom placeholder copy if self

* navigate to /profile/:handle

* add name to title

* show header on desktop

src/lib/routes/types.ts

@@ -18,6 +18,7 @@ export type CommonNavigatorParams = {
   ProfileFollowers: {name: string}
   ProfileFollows: {name: string}
   ProfileKnownFollowers: {name: string}
+  ProfileSearch: {name: string; q?: string}
   ProfileList: {name: string; rkey: string}
   PostThread: {name: string; rkey: string}
   PostLikedBy: {name: string; rkey: string}