extract methods from _check_instance_output
extract _extract_allocation_owner_id
restructure if/else block

I removed one branch:

    else {
        die $class->error_message("Unexpected condition in " . __PACKAGE__ . "::_check_instance_output");
    }

This branch was essentially unreachable due to
"_cleanup_legacy_non_software_result_data".  I did not find any log
messages containing "_check_instance_output" in the last 30 days.
simplify nested if (cleanup)
simplify nested if (validate)
extract _validate_found_allocation
extract _validate_missing_allocation
simplify if statements

instance_output is always a link here
instrument symlink removal
unlink purged and invalid allocations
check for archived allocations
do not make tarballs for symlinked data
remove use of unstable ~~ operator
fix missing `$_ eq` in grep
Merge pull request #354 from mark-burnett/dv2-purged-allocations

DV2 DetectionBase knows more about allocation statuses