* tests: make `spack url [stats|summary]` work on mock packages
Mock packages have historically had mock hashes, but this means they're also invalid
as far as Spack's hash detection is concerned.
- [x] convert all hashes in mock package to md5 or sha256
- [x] ensure that all mock packages have a URL
- [x] ignore some special cases with multiple VCS fetchers
* url stats: add `--show-issues` option
`spack url stats` tells us how many URLs are using what protocol, type of checksum,
etc., but it previously did not tell us which packages and URLs had the issues. This
adds a `--show-issues` option to show URLs with insecure (`http`) URLs or `md5` hashes
(which are now deprecated by NIST).
c309adb4b3