test infra: adds book-keeping for rerunnable tests

Also adds full path info for exceptional exits and timeouts when
no test method is currently running.

Adds --rerun-all-issues command line arg.  If specified, all
test issues are eligible for rerun.  If not specified, only tests
marked flakey are eligible for rerun.

The actual rerunning will occur in an upcoming change.  This
change just handles tha accounting of what should be rerun.

llvm-svn: 255438