New rule `no-sync-act`: discourages sync usage of `act`

Name for new rule

no-sync-act

Description of the new rule

As per https://react.dev/reference/react/act#await-act-async-actfn
sync usage of act is discouraged:

We recommend using act with await and an async function. Although the sync version works in many cases, it doesn’t work in all cases and due to the way React schedules updates internally, it’s difficult to predict when you can use the sync version.

We will deprecate and remove the sync version in the future.

Testing Library feature

act

Testing Library framework(s)

React

What category of rule is this?

Warns about a potential error

Optional: other category of rule

No response

Code examples

The new rule would fail on

act(() => {
await act(() => {
act(async () => {

and pass on

await act(async () => {

Anything else?

No response

Do you want to submit a pull request to make the new rule?

No

No implementation files or tests are named. Locate existing act-related rules and their React rule tests, then use the issue's examples to define the warning for synchronous act usage and the accepted awaited async form.