GH-43510: [PYTHON] Move NumPy specific tests to separate test file.

[Reranko05]

This PR reorganizes Python array tests by moving NumPy-specific tests out of
python/pyarrow/tests/test_array.py into a new file,
python/pyarrow/tests/test_array_numpy.py.

The goal is to keep test_array.py focused on core Arrow array behavior while
isolating tests that depend on NumPy, which is an optional runtime dependency.

What this PR does:

• Moves tests explicitly marked with @pytest.mark.numpy into a separate file
• Keeps test logic, assertions, and coverage unchanged
• Reduces the size and scope of test_array.py
• Improves test organization and maintainability

What this PR does NOT do:

• No behavioral or functional changes
• No new tests added
• No changes to NumPy or Arrow semantics

Related issue: GH-43510

• GitHub Issue: [Python] Move tests that are explicitly about conversion to/from numpy on test_array.py to a separate file #43510

[raulcd]

Can you remove these empty lines?

[Reranko05]

Removed the extra blank lines. Thanks for pointing it out.

[raulcd]

There are several linting failures, that's why the CI job is failing, can you take a look?
https://github.com/apache/arrow/actions/runs/21179073114/job/60943377596?pr=48899

[Reranko05]

Hello @raulcd, I will look into it and get back to you.
Thanks