Fix SplitView sample layout issue when pane is on the right side

[AndrewKeepCoding]

Description

This PR updates the SplitView sample to switch layouts dynamically depending on the pane's placement (left or right).

Motivation and Context

Fixes #322.

How Has This Been Tested?

Manually tested.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

[AndrewKeepCoding]

@marcelwgn Do you think we should horizontally stretch the SplitView to the options panel (as suggested in the issue)? I feel it looks too wide for this sample.

[niels9001]

/azp run

[marcelwgn]

@marcelwgn Do you think we should horizontally stretch the SplitView to the options panel (as suggested in the issue)? I feel it looks too wide for this sample.

I agree that it would look if we stretch it to the options panel. I think we should have a fixed maximum width for it.

[marcelwgn]

Thank you for fixing this! Changes look good, just a little bit of cleanup is necessary.

[marcelwgn]

/azp run