enhancement(stdlib): add IPv4-mapped IPv6 support to ip_cidr_contains

[milas]

Summary

Support IPv4-mapped IPv6 addresses/ranges with ip_cidr_contains.

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

How did you test this PR?

Existing + new unit test cases.

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on
  our guidelines.
• No. A maintainer will apply the "no-changelog" label to this PR.

(will add changelog entry after initial review / feedback)

Checklist

• Our CONTRIBUTING.md is a good starting place.
• (N/A) If this PR introduces changes to LICENSE-3rdparty.csv, please
  run dd-rust-license-tool write and commit the changes. More details here.
• For new VRL functions, please also create a sibling PR in Vector to document the new function.

I'm happy to open Vector PR later with additional examples/prose for the new cases.

References

I did not find any open issues/PRs for this already, sorry if I missed one!