Better package name matching for Nexus

[craddm]

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⤴️ Summary

Modifies how the configure_nexus.py script creates Nexus Content Selector search patterns, allowing CRAN packages to include capital letters and following the complete package name with _ (e.g. RPostgreSQL_) to prevent overly permissive matching and installation of non-allow-listed packages.

Note that to perform the fix I had to teardown the existing proxy VM and redeploy it. The issues cannot be fixed by modifying the local copy of the configure_nexus.py script, as the important copy is on the docker container running Nexus on the VM. It's not clear to me how to modify that without redeploying the VM entirely (but it may be clear to someone else!).

🌂 Related issues

Closes #1445
Closes #1439

🔬 Tests

Packages with capital letters can now be installed correctly on Tier 3 VMs:

Packages that are not on the allowlist but that had names that would still match search patterns for other packages (e.g. csvread, which matched the pattern for csv) can no longer be installed and will correctly return a 403 Forbidden code:

[JimMadge]

Excellent, two birds with one stone!

[edwardchalstrey1]

Note that to perform the fix I had to teardown the existing proxy VM and redeploy it. The issues cannot be fixed by modifying the local copy of the configure_nexus.py script, as the important copy is on the docker container running Nexus on the VM. It's not clear to me how to modify that without redeploying the VM entirely (but it may be clear to someone else!).

@JimMadge is there any reason we shouldn't just go ahead and do this for prod4? At the moment the only tier 3 SRE is Edon so it seems like the only consideration is a small amount of downtime for R package installation

[JimMadge]

@edwardchalstrey1 I don't think that should be a problem.