Fixed RankWidget

[grzesiek2010]

Closes #2980

What has been done to verify that this works as intended?

I tested the form attached to the issue on different devices.

Why is this the best possible solution? Were any other approaches considered?

We use nested scrollable elements in RankWIdget so we should use NestedScrollView for that, not ordinary ScrollView which works well only on older devices.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

This change should just fix the issue. It's only related to RankWidget so testing that widget would be enough.

Do we need any specific form for testing your changes? If so, please attach one.

The form attached to the issue.

Does this change require updates to documentation? If so, please file an issue here and include the link below.

No.

Before submitting this PR, please make sure you have:

• run ./gradlew checkAll and confirmed all checks still pass OR confirm CircleCI build passes and run ./gradlew connectedDebugAndroidTest locally.
• verified that any code or assets from external sources are properly credited in comments and/or in the about file.
• verified that any new UI elements use theme colors. UI Components Style guidelines

[mmarciniak90]

Tested with success

Verified on Android: 4.2, 4.4, 5.1, 6.0, 7.0, 8.1

Tested cases:

• rank-field-list form
• Rank widget in All widgets form
• scroll on horizontal and vertical device orientation
• locking screen
• device rotation

@opendatakit-bot unlabel "needs testing"
@opendatakit-bot label "behavior verified"