Stub the Windows module's `Gestures` map (#4383)

## Description

`RNGestureHandlerModule.windows.ts` exists so `react-native-windows`
apps compile. Every method is a no-op, yet it value-imported all 8
web-engine handler classes just to build the `Gestures` map, pulling the
entire engine into Windows bundles for a module that never instantiates
anything.

## Test plan

- `yarn ts-check` clean (the `satisfies` clause pins key names to the
web map); `yarn test` 103/103; `yarn lint:js` 0 errors
- Type-stripped emit: zero import statements - the Windows resolution is
dependency-free at runtime