Do not hide media from your own user by default (#29797)

* Always show media from your own user

* Update usages of useMediaVisible

* lint

* Add a test for HideActionButton

* Improve docs

* Document the event

* fixup test

* Allow users to hide their own media if they wish.

* Update tests

* remove a check\

* tweak

* tweak

test/unit-tests/components/views/messages/HideActionButton-test.tsx

@@ -48,6 +48,7 @@ describe("HideActionButton", () => {
     beforeEach(() => {
         cli = getMockClientWithEventEmitter({
             getRoom: jest.fn(),
+            getUserId: jest.fn(),
         });
     });
     afterEach(() => {