Refactor vertical scrollbar to only be visible when text content overflows

[shwanton]

Please select one of the following

• I am removing an existing difference between facebook/react-native and microsoft/react-native-macos 👍
• I am cherry-picking a change from Facebook's react-native into microsoft/react-native-macos 👍
• I am making a fix / change for the macOS implementation of react-native
• I am making a change required for Microsoft usage of react-native

Summary

#1366 Added a vertical scrollbar to all Multiline TextInputs. This change caused some visual regression since it was showing scrollbars even if the text content did not overflow the view.

There are also instances where we don't want the vertical scrollbar to be visible. For this edge case we can pass hideVerticalScrollIndicator to always hide the scrollbar.

NOTE #1244 Adds support for disabling scrollview. Once that PR is merged, I will update this to also not show the vertical scrollbar when scrolling is disabled.

Fixes #1368

Changelog

• Only show the vertical scrollbar if the text content overflows bounds of containing view.
• Hide the scrollbar when hideVerticalScrollIndicator is passed as prop

[Fixed] [macOS] - Optionally hide the vertical scrollbar & only display when text overflows containing view

Test Plan

Pasting text that overflows container view

CleanShot.2022-09-26.at.18.14.59.mp4

Input has pre-populated value that overflows container view

CleanShot.2022-09-26.at.18.16.41.mp4

Input has pre-populated value that does not overflow container view

CleanShot.2022-09-26.at.18.17.10.mp4

passing hideVerticalScrollIndicator prop as true will always hide the vertical scrollbar

CleanShot.2022-09-26.at.18.19.19.mp4

[shwanton]

@Saadnajmi Just tested against master & this is ready to be merged.

[chiuam]

Looks good, thanks for making this change!