Add verify command

[RobertRosca]

PR adds a verify command which reads the spack install manifest files inside a view and checks that all of the files which were installed by spack are still symlinks pointing to the correct locations.

If they are not, then a --fix flag can be passed to replace the files with the correct symlinks.

Todo:

• Testing
• Update to readme/docs

[codecov]

Codecov Report

Base: 93.02% // Head: 86.92% // Decreases project coverage by -6.10% ⚠️

Coverage data is based on head (c390494) compared to base (e3a9906).
Patch coverage: 42.10% of modified lines in pull request are covered.

❗ Current head c390494 differs from pull request most recent head bc15120. Consider uploading reports for the commit bc15120 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #3      +/-   ##
==========================================
- Coverage   93.02%   86.92%   -6.11%     
==========================================
  Files          13       14       +1     
  Lines         416      459      +43     
==========================================
+ Hits          387      399      +12     
- Misses         29       60      +31     

Impacted Files	Coverage Δ
src/pyvarium/installers/base.py	80.59% <0.00%> (-1.23%)	⬇️
src/pyvarium/installers/spack.py	80.85% <31.81%> (-15.31%)	⬇️
src/pyvarium/cli/verify.py	33.33% <33.33%> (ø)
src/pyvarium/cli/__init__.py	82.00% <100.00%> (+0.36%)	⬆️
src/pyvarium/cli/new.py	100.00% <100.00%> (+4.34%)	⬆️
src/pyvarium/config.py	92.72% <100.00%> (ø)
src/pyvarium/installers/pipenv.py	100.00% <100.00%> (ø)

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[lgtm-com]

This pull request fixes 1 alert when merging c390494 into 4fea4bb - view on LGTM.com

fixed alerts:

• 1 for Unused import

---

Heads-up: LGTM.com's PR analysis will be disabled on the 5th of December, and LGTM.com will be shut down ⏻ completely on the 16th of December 2022. Please enable GitHub code scanning, which uses the same CodeQL engine ⚙️ that powers LGTM.com. For more information, please check out our post on the GitHub blog.

[lgtm-com]

This pull request fixes 1 alert when merging bc15120 into 4fea4bb - view on LGTM.com

fixed alerts:

• 1 for Unused import

---

Heads-up: LGTM.com's PR analysis will be disabled on the 5th of December, and LGTM.com will be shut down ⏻ completely on the 16th of December 2022. Please enable GitHub code scanning, which uses the same CodeQL engine ⚙️ that powers LGTM.com. For more information, please check out our post on the GitHub blog.