Improve methods to cleanup collections and buckets (GSI-902)

[Cito]

PR #115 changed the behavior of the empty_buckets method in an attempt to make it more similar to empty_collections.

Before, it used to only empty the buckets that were populated using the fixture. Now, it empties all existing buckets that can be accessed. This has the advantage that the fixture does not need to track which buckets were populated and can also clean buckets that were not populated using the fixture. However, this can now also empty buckets in the S3 instance that are not part of the application or tests and not supposed to be touched.

Therefore, this PR adds parameters for specifying the collections and buckets to be emptied in addition to the parameter that already allowed specifying which collections and buckets should be excluded.

In addition, these parameters are now made keyword-only to avoid mistakes when calling these methods.

Another question in this context was how to handle objects that were not created using hexkit and therefore can have names that do not comply with the validation rules for ids implemented in hexkit. These will cause validation errors when hexkit tries to delete them when emptying the containing bucket. This could happen for instance with object names that contain forward slashes or start with a dot. In these cases, we intentionally let the error bubble up instead of trying to delete these objects despite the error or silently ignore them, because they usually indicate a problem that should be made apparent.

However, this PR also facilitates using different validation rules for object names, by not hard coding the regular expression used for validation, but exposing it as an attribute that can be overridden. Also, the PR relaxes the validation a little bit by allowing underscores and longer object names. Forward slashes are still not allowed by default, though.

[coveralls]

Pull Request Test Coverage Report for Build 9956350161

Details

• 41 of 47 (87.23%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.06%) to 91.697%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/hexkit/providers/mongodb/testutils.py	10	12	83.33%
src/hexkit/providers/s3/testutils/_fixtures.py	25	29	86.21%

Totals
Change from base Build 9839054397:	-0.06%
Covered Lines:	1756
Relevant Lines:	1915

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💛 - Coveralls

[TheByronHimes]

Looks good on the whole. I only saw a few small things.