Migrate built-in extensions to use manifest-based activate hooks (#5435)

* Convert jQuery/IIFE wrappers to exported init() functions and register activate hooks in 8 extension manifests

* Convert remaining extensions to exported init() with activate hooks and await initExtensions()

- Convert jQuery/IIFE wrappers to exported init() functions in expressions, memory, quick-reply, regex, stable-diffusion, translate, tts, and vectors extensions

- Register init functions as activate hooks in extension manifests

- Properly await async initExtensions() in firstLoadInit()

* Fix eslint

---------

Co-authored-by: Cohee <18619528+Cohee1207@users.noreply.github.com>

public/scripts/extensions/token-counter/index.js

@@ -101,7 +101,7 @@ async function doCount() {
     return count;
 }
 
-jQuery(() => {
+export function init() {
     const buttonHtml = `
         <div id="token_counter" class="list-group-item flex-container flexGap5">
             <div class="fa-solid fa-1 extensionsMenuExtensionButton" /></div>` +
@@ -115,4 +115,4 @@ jQuery(() => {
         returns: 'number of tokens',
         helpString: 'Counts the number of tokens in the current chat.',
     }));
-});
+}