deep archive misses products that specify primary products using lower case 'p'

[jordanpadams]

🐛 Describe the bug

The SIP/transfer/checksum manifest files in a Deep Archive package do not list a primary basic product designated by lowercase “p” in the collection inventory file. The Standards do not appear to restrict the membership value to uppercase “P” or “S” in a collection inventory file.

📜 To Reproduce

Run pds-deep-archive against a collection specifying a primary product with P instead of p

🕵️ Expected behavior

pds-deep-archive should be case agnostic when it comes to specifying primary/secondary products.

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🦄 Related requirements

⚙️ Engineering Details

[nutjob4life]

The code for "p-lines" currently is:

_pLineMatcher = re.compile(r'^P,\s*([^\s]+)::([^\s]+)')

So it currently matchies capital P. I think the issue title and "to reproduce" are flipped.

I'll add a test case that includes mixed case P/p to test in case (see what I did there 😏) case-insensitivity is working.