chore: Move editor into codebase (#2930)

shared/typings/gemoji.d.ts

@@ -0,0 +1 @@
+declare module "gemoji";

shared/typings/markdown-it-mark.d.ts

@@ -0,0 +1,5 @@
+declare module "markdown-it-mark" {
+  function plugin(md: any): void;
+
+  export = plugin;
+}

shared/typings/prosemirror-model.d.ts

@@ -0,0 +1,10 @@
+import "prosemirror-model";
+
+declare module "prosemirror-model" {
+  interface Slice {
+    // this method is missing in the DefinitelyTyped type definition, so we
+    // must patch it here.
+    // https://github.com/ProseMirror/prosemirror-model/blob/bd13a2329fda39f1c4d09abd8f0db2032bdc8014/src/replace.js#L51
+    removeBetween(from: number, to: number): Slice;
+  }
+}