Odd setclrpath interaction with singlefile

When attaching to a live process, a unix singlefile that has no collocated dac will need to have its DAC pointed at via directory backed symbol server or via setclrpath. the latter resets on continue since runtimes are flushed in between continuations, so it needs to be added every time. This is unique to live singlefile apps.

Start by reproducing attachment to a live Unix single-file app without a collocated DAC, using setclrpath and continuing execution. Observe when runtimes are flushed and verify that the DAC path remains available or is reapplied after each continuation; done means setclrpath works consistently for this scenario.

Written by the indexing model from the issue text.