Migrate IIconElementHandler to .NET MAUI

### Description

Currently the SwipeView uses IIconElementHandler to load icon images which it is doing via compatibility.

For now I've just copied over each implementation into an extension method so that icon loading works for SwipeView

### (Public) API Changes

TBD

### Usage Scenarios

N/A

### Backward Compatibility

N/A

### Difficulty

Low

Start by locating SwipeView and the copied icon-loading extension methods, then trace their use of IIconElementHandler and the compatibility implementation. Done means the icon-loading behavior works through the .NET MAUI implementation without relying on compatibility; the issue does not name specific files or tests to run.

Written by the indexing model from the issue text.