[flow-strict] Flow strict ScrollView; get rid of InternalScrollViewType

[thymikee]

Summary

Relates to #22100.

I left 2 $FlowFixMes as I was not sure how to handle generic React.Element<> and which native props can I pass to ScrollView (would be cool to document it once we got proper types there).

I also got rid of InternalScrollViewType because we have better typings in original ScrollView now.

Test Plan

Flow passes.

Changelog

[General] [Fixed] - Stricter Flow typings for ScrollView

[RSNara]

Looks good!

[facebook-github-bot]

@RSNara has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[grabbou]

@facebook-github-bot shipit

[grabbou]

Thank you for sending this PR and to all the reviewers!

[facebook-github-bot]

@grabbou is landing this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[hramos]

This may require some internal work to update some internal callsites to ensure Flow check does not fail.

[thymikee]

Understood. The typings around ScrollView increased significantly with this PR (by just removing the InternalScrollViewType) so I would expect some failures here and there :D. But technically that's a good thing. Hopefully it will be smooth upgrade.

[facebook-github-bot]

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[thymikee]

Updated the diff, but didn't test it on RNTester yet. Feel free to comment on Flow typings though :)

[facebook-github-bot]

@cpojer has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[cpojer]

Let's see if this passes Flow internally.

[cpojer]

Imported to see latest internal Flow errors and discussed with @thymikee. Will leave this PR for @RSNara to land.

[thymikee]

@RSNara @TheSavior I've tested this on RNTester for unexpected regressions and it seems just fine. Typings also work, e.g. when you add .flowconfig to RNTester directory.

There are still open questions (e.g. whether getScrollResponder() from non-ScrollView components to return ?ScrollView as it is currently or the real ScrollView & ScrollResponder.Mixin?) so I'd like your input.

[facebook-github-bot]

@RSNara has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[facebook-github-bot]

@RSNara has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[react-native-bot]

This pull request was successfully merged by @thymikee in fe533a4.

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