Add random regular graph generator to rustworkx

[lueckem]

The random_regular_graph generator was already merged into rustworkx-core in #1423. This PR adds the function to rustworkx.
Closes #1391.

• I ran rustfmt locally
• I have added the tests to cover my changes.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.

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All committers have signed the CLA.

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[IvanIsCoding]

Thanks. This looks straightforward, the bulk on the comments were in the previous PR. I am glad we wrapped this up

[coveralls]

Coverage Report for CI Build 25827482011

Coverage increased (+0.5%) to 94.666%

Details

• Coverage increased (+0.5%) from the base build.
• Patch coverage: 23 of 23 lines across 2 files are fully covered (100%).
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	19816
Covered Lines:	18759
Line Coverage:	94.67%
Coverage Strength:	949495.62 hits per line

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💛 - Coveralls