fix(switch): ensure ability to set a value

Author: zeroedin

elements/pf-v6-switch/demo/form-association.html

@@ -3,7 +3,7 @@
 description: A switch can participate in forms. It submits "on" when checked and is omitted when unchecked. Use the reset button to restore the initial state.
 ---
 <form id="settings-form">
-  <pf-v6-switch name="notifications" checked>Notifications</pf-v6-switch>
+  <pf-v6-switch name="notifications" checked value="im-on">Notifications</pf-v6-switch>
   <br><br>
   <button type="submit">Submit</button>
   <button type="reset">Reset</button>

elements/pf-v6-switch/pf-v6-switch.ts

@@ -47,6 +47,9 @@ export class PfV6Switch extends LitElement {
   /** Reverses the layout so the label appears before the toggle. */
   @property({ reflect: true, type: Boolean }) reversed = false;
 
+  /** Form value defaults to undefined */
+  @property({ type: String }) value?;
+
   #initialChecked = false;
 
   get #classes() {
@@ -92,7 +95,7 @@ export class PfV6Switch extends LitElement {
     this.#internals.ariaChecked = String(!!this.checked);
     this.#internals.ariaDisabled = String(!!this.disabled);
     this.#internals.ariaLabel = this.accessibleLabel || null;
-    this.#internals.setFormValue(this.checked ? 'on' : null);
+    this.#internals.setFormValue(this.checked ? (this.value ?? null) : null);
   }
 
   override render(): TemplateResult<1> {