feat: Disable session lock when running in element-desktop (#30643)

* feat: Disable session lock when running in element-desktop

* feat: Use Platform abstractions over direct invocation for session lock.

* fix: Remove window.electron checks from session lock methods.

* docs: Remove extraneous doc comments.

* feat: Convert BasePlatform session methods to abstract methods.

* fix: Check for PlatformPeg instance in session lock.

* fix: Remove async marker from checkSessionLockFree

test/unit-tests/components/structures/MatrixChat-test.tsx

@@ -1632,6 +1632,10 @@ describe("<MatrixChat />", () => {
     });
 
     describe("Multi-tab lockout", () => {
+        beforeEach(() => {
+            mockPlatformPeg();
+        });
+
         afterEach(() => {
             Lifecycle.setSessionLockNotStolen();
         });
@@ -1677,6 +1681,8 @@ describe("<MatrixChat />", () => {
             beforeEach(() => {
                 // make sure we start from a clean DOM for each of these tests
                 document.body.replaceChildren();
+                // use the MockPlatform
+                mockPlatformPeg();
             });
 
             function simulateSessionLockClaim() {