To make it easier to see how package hashes change and how they are computed, add two
commands:
* `spack pkg source <spec>`: dumps source code for a package to the terminal
* `spack pkg source --canonical <spec>`: dumps canonicalized source code for a
package to the terminal. It strips comments, directives, and known-unused
multimethods from the package. It is used to generate package hashes.
* `spack pkg hash <spec>`: This gives the package hash for a particular spec.
It is generated from the canonical source code for the spec.
- [x] `add spack pkg source` and `spack pkg hash`
- [x] add tests
- [x] fix bug in multimethod resolution with boolean `@when` values
Co-authored-by: Greg Becker <becker33@llnl.gov>