Fix Grid Starred Row/Column regressions

[hartez]

Description of Change

These changes address some regressions in starred column handling which PR #11336 introduced.

Partial starred columns (e.g., columns with a GridLength of 0.3*) were causing columns to over-contract when fitting to a width during measurement; this caused them to squeeze to the left and not fill up the full target width. The measurements now account for columns with factors less than 1, as do the automated tests.

Starred rows were not accounting for minimum row sizes when determining how far they could contract to fit into target sizes; this caused them to contract too far and not fill vertical spaces properly. The measurements now account for this, as do the automated tests.

Issues Resolved

• fixes RelativeLayout is not taking full screen since XamarinForms 4.8 update #11742
• fixes [Bug] ListView margin inside Grid starred row is calculated incorrectly #11835
• fixes Xamarin Form v 4.8.0.1269 ScrollView not filling in space  #11796

API Changes

None

Platforms Affected

• Core/XAML (all platforms)

Behavioral/Visual Changes

None

Before/After Screenshots

Not applicable

Testing Procedure

Automated tests

PR Checklist

• Targets the correct branch
• Tests are passing (or failures are unrelated)

[jsuarezruiz]

@hartez Maybe #11796 is fixed too with the changes.

[hartez]

@hartez Maybe #11796 is fixed too with the changes.

Might be, but they haven't provided us enough info to verify that.

[aliyailina]

The problem has appeared for me after upgrading. I have:
RowDefinition Height="Auto"
RowDefinition Height="Auto"
RowDefinition Height="3*"
RowDefinition Height="2*"

It worked nice, but after upgrading the elements in this Grid are less than it was.