Feat: Support prefix appending in maven uploading and deletion

[ligangty]

This pr will let uploading and deletion process of maven releases have support to append the prefix as root dir to all files.

[ligangty]

@jdcasey this pr only handles the maven process. For npm, it will be in another pr.

[coveralls]

Pull Request Test Coverage Report for Build 1535091559

• 60 of 65 (92.31%) changed or added relevant lines in 8 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.4%) to 82.322%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
charon/pkgs/indexing.py	13	14	92.86%
charon/pkgs/maven.py	21	22	95.45%
charon/utils/archive.py	0	1	0.0%
charon/cmd/command.py	0	2	0.0%

Totals
Change from base Build 1533707752:	0.4%
Covered Lines:	1113
Relevant Lines:	1352

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💛 - Coveralls

[ligangty]

@jdcasey @geored The bandit check failed on the ssl disablement of the requests lib, but when I'm doing tests I found it always failed to download from our internal tarball sites by the ssl checking. I'm not sure a better solution yet for this. Do you have any suggestions on this?

[jdcasey]

These bandit failures seem to be having a problem not related to your code. It's either a problem in the linter or in the default verify value in requests for those packages. It's important to realize too that it could be a conflict between system packages (python-requests RPM) and pip packages. I think we should proceed and let someone fix the underlying package.