Refactor pad_side and strip_type enums into side_type enum

[davidwendt]

Description

Refactors the cudf::strings::pad_side and cudf::strings::strip_type to a single enum cudf::strings::side_type. These have the same values as used by cudf::strings::pad and cudf::strings::strip Moving these into a single header helps with reusing them in the strings_udf work. Updates to gtests and cython code layers are also included.

Checklist

• [x] I am familiar with the Contributing Guidelines.
• [x] New or existing tests cover these changes.
• [x] The documentation is up to date with these changes.

[codecov[bot]]

Codecov Report

:exclamation: No coverage uploaded for pull request base (branch-22.10@e5b92df). Click here to learn what that means. The diff coverage is n/a.

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[davidwendt]

This should be marked as a breaking change since the public enums have been moved/renamed.

[davidwendt]

@gpucibot merge