feat: switch to remark from markdown-it (big)

* replaces old mentions with avatar and display name
* renders things directly through React
* replaces most of the markdown hacks with custom AST components
* adds a tooltip to codeblock "copy to clipboard"

src/components/markdown/plugins/channels.tsx

@@ -0,0 +1,21 @@
+import { Link } from "react-router-dom";
+
+import { clientController } from "../../../controllers/client/ClientController";
+import { createComponent, CustomComponentProps } from "./remarkRegexComponent";
+
+export function RenderChannel({ match }: CustomComponentProps) {
+    const channel = clientController.getAvailableClient().channels.get(match)!;
+
+    return (
+        <Link
+            to={`${
+                channel.server_id ? `/server/${channel.server_id}` : ""
+            }/channel/${match}`}>{`#${channel.name}`}</Link>
+    );
+}
+
+export const remarkChannels = createComponent(
+    "channel",
+    /<#([A-z0-9]{26})>/g,
+    (match) => clientController.getAvailableClient().channels.has(match),
+);