Bring sync api back for a few minor verions

[fa93hws]

Problem description

One breaking change introduced in v14 is that almost all api is changed to async now.
It become a nightmare to upgrade testing library now because we lots of frontend engineer works on the monorepo and it's extremely hard to get all usage changed in one go.

I think for a breaking api that has such a big impact maybe better to have a smoother migration plan?

Suggested solution

Bring the sync api back for a few minor version and decorated as deprecated. They can be removed from next major version.
So that we can upgrade first, enforce a linting rule and fix the rest progressively.

Additional context

No response

[ethanneff]

yeah we are still on v13 because v14 was a nightmare to migrate

[eddielee394]

Yeah, i"m in the process of doing the upgrade now on a medium sized application and it's been brutal. We have 3 other FE apps that we still have to do that I'm genuinely not looking forward to.