feat: Create lightning/flowSupport stub (#477)

* feat: add flowSupport stub

This adds a missing stub for lightning/flowSupport. Tackes #448

* Apply suggestion from @wjhsf

---------

Co-authored-by: Will Harney <62956339+wjhsf@users.noreply.github.com>

Author: FedeAbella

src/lightning-stubs/flowSupport/flowSupport.js

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2025, salesforce.com, inc.
+ * All rights reserved.
+ * SPDX-License-Identifier: MIT
+ * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT
+ */
+export const FlowAttributeChangeEventName = 'lightning__flowattributechange';
+export const FlowNavigationBackEventName = 'lightning__flownavigationback';
+export const FlowNavigationNextEventName = 'lightning__flownavigationnext';
+export const FlowNavigationPauseEventName = 'lightning__flownavigationpause';
+export const FlowNavigationFinishEventName = 'lightning__flownavigationfinish';
+
+export class FlowAttributeChangeEvent extends CustomEvent {
+    constructor() {
+        super(FlowAttributeChangeEventName, { bubbles: true, composed: true });
+    }
+}
+
+export class FlowNavigationBackEvent extends CustomEvent {
+    constructor() {
+        super(FlowNavigationBackEventName, { bubbles: true, composed: true });
+    }
+}
+
+export class FlowNavigationNextEvent extends CustomEvent {
+    constructor() {
+        super(FlowNavigationNextEventName, { bubbles: true, composed: true });
+    }
+}
+
+export class FlowNavigationPauseEvent extends CustomEvent {
+    constructor() {
+        super(FlowNavigationPauseEventName, { bubbles: true, composed: true });
+    }
+}
+
+export class FlowNavigationFinishEvent extends CustomEvent {
+    constructor() {
+        super(FlowNavigationFinishEventName, { bubbles: true, composed: true });
+    }
+}