handle panics during make() gracefully

[andrewrk]

Extracted from #14647.

Currently, if any build steps panic during make(), they dump stack trace to stderr, and the thread is lost. Instead, the stack trace and panic message should be captured as a step error, and a new thread should be spawned to replace the one that died.

Care should be taken to not accidentally capture panics from the build runner itself in this manner.

[matu3ba]

Related / where some code could be yanked from for the logic: #14351. Comparing against the global build runner thread id should be sufficient.
Not sure about the spawning logic: One either needs to store the thread ids in memory or spawn them from build runner thread.