Add a section to the lock file to track the Spack version/commit that produced
an environment. This should (eventually) enhance reproducibility, though we
do not currently do anything with the information. It just adds to provenance
at the moment.
Changes include:
- [x] adding the version/commit to `spack.lock`
- [x] refactor `spack.main.get_version()
- [x] fix a couple of environment lock file-related typos
8e18297cf2