perf(webui): load optional password generation on demand

webui/tests/password-generator.test.tsx

@@ -66,6 +66,16 @@ assert(!markup.includes("password-generator-dialog"), "the generator dialog stay
 assert(markup.includes('data-help-context-id="access.authentication.password"'), "the owner context reaches the password field and its actions");
 assert(markup.includes('data-help-module-id="access"'), "the password field retains its documentation owner");
 
+for (const flags of [{}, { generator: true, disabled: true }, { generator: true, readOnly: true }]) {
+  const unavailableMarkup = renderToStaticMarkup(
+    <PlatformLanguageProvider>
+      <PasswordField value="fixture-password" onValueChange={() => undefined} {...flags} />
+    </PlatformLanguageProvider>
+  );
+  assert(!unavailableMarkup.includes('aria-label="Generate password"'), "unavailable generation cannot open the optional dialog");
+  assert(!unavailableMarkup.includes("module-load-progress"), "closed generators never begin loading while rendering a field");
+}
+
 const dialogMarkup = renderToStaticMarkup(
   <PlatformLanguageProvider>
     <PasswordGeneratorDialog