respect metadata_directory

[dimbleby]

Fixes python-poetry/poetry#1078

I'm not sure how useful this really is, but it seems to be what the spec asks for.

It should anyway be an improvement on the half-hearted existing implementation which:

• provided prepare_metadata_for_build_wheel() but then didn't respect metadata_directory in build_wheel()
• duplicated code (but not fully, ie there was divergence between the two metadata-building places)

It might have been even simpler just to remove prepare_metadata_for_build_wheel() altogether - it's not mandatory - but whatever.

pip wheel . executes this code path: that this works is perhaps a more convincing proof that the MR is OK than the unit test.

Change in file permission unit test is because I now see these files getting 100644 rather than just 644. Not entirely sure why that has changed but it seems benign so I've allowed it.

[sonarcloud]

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0.0% Duplication

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information