This PR fixes the performance regression reported in #31985 and a few
other issues found while refactoring the spack mirror create command.
Modifications:
* (Primary) Do not require concretization for
`spack mirror create --all`
* Forbid using --versions-per-spec together with --all
* Fixed a few issues when reading specs from input file (specs were
not concretized, command would fail when trying to mirror
dependencies)
* Fix issue with default directory for spack mirror create not being
canonicalized
* Add more unit tests to poke spack mirror create
* Skip externals also when mirroring environments
* Changed slightly the wording for reporting (it was mentioning
"Successfully created" even in presence of errors)
* Fix issue with colify (was not called properly during error
reporting)
1913dc2da3