Add ability to include and exclude CODEOWNERS rules for roulette

What does this MR do and why?

This MR adds the ability to configure reviewer roulette with the following options when it comes to CODEOWNERS approvals:

• Include specified optional CODEOWNERS sections via config.included_optional_codeowners_sections_for_roulette
• Exclude specified required CODEOWNERS sections via config.excluded_required_codeowners_sections_for_roulette

The reasons to provide these options include, but are not limited to:

• Allowing us to recommend roulette reviewers based on CODEOWNERS without making the relevant sections required.
• Allowing us to require CODEOWNERS sections that already have existing roulette support without adding a duplicate suggestion.

For more context, see #45 (closed)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.