We are planning to switch to using full hashes for Spack specs, which means that the
package hash will be included in the deployment descriptor. This means we need a more
robust package hash than simply dumping the `repr` of the AST.
The AST repr that we previously used for package content is unreliable because it can
vary between python versions (Python's AST actually changes fairly frequently).
- [x] change `package_hash`, `package_ast`, and `canonical_source` to accept a string for
alternate source instead of a filename.
- [x] consolidate package hash tests in `test/util/package_hash.py`.
- [x] remove old `package_content` method.
- [x] make `package_hash` do what `canonical_source_hash` was doing before.
- [x] modify `content_hash` in `package.py` to use the new `package_hash` function.
Co-authored-by: Danny McClanahan <1305167+cosmicexplorer@users.noreply.github.com>
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