Update IntelliSense compiler path based on target selected

### Brief Issue Summary
I would like to raise a feature request to update the IntelliSense compiler path based on the selected target.

### Expected:
Working on projects where different targets use different compiles, the compile path should be updated based on the selected target.

### Apparent Behavior:
IntelliSense will use the same compiler no matter which target is selected.

Start by tracing how the selected target is represented and where IntelliSense chooses its compiler path. Reproduce the behavior with a project containing targets that use different compilers, then verify that changing the selected target changes the IntelliSense compiler path accordingly. The issue has no named files or tests, so locating the relevant entry points will require project familiarity.

Written by the indexing model from the issue text.