Add test utilities to mock `useLazy*` and `use*`

[huang-julien]

Describe the feature

Hey 👋

First, good job with the module. Love using it so far.
I encountered a small issues while testing. Mocking open fetch composable is kinda hard due to typescript not being able to infer the return type of the composable.

ex:

// @ts-expect-error need this as TS is not able to infer
vi.mocked(useOpenFetch).mockImplementation((url) => {
  if (url === '/some-api') {
   return Promise.resolve({ data: ref({}), error: ref({}), /**.....**/ })
 }
  throw new Error('')
})

would be nice to provide some utilities to help users to mock those composables

Additional information

• Would you be willing to help implement this feature?

Final checks

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• Check existing discussions and issues.