devtools

3fee03da - Add support for system isolates to isolate selector while in VM developer mode (#2947)

Add support for system isolates to isolate selector while in VM developer mode (#2947) - Removed 'Isolate' from the isolate selector, replaced with 'forking' icon for isolates and 'gear' for system isolates. - Added tooltip for the isolate selector: 'Selected Isolate'. - Added 'No source available' path for CodeView. - Disable various debugger controls for system isolates.