fix(issue): display list of comments in raw format

Description

Display list of comments for the raw output of issue view --comments command.

Related Issues

Resolves #1028 (closed)

How has this been tested?

• With new/refactored tests
• Via glab issue view --comments --system-logs 9 > issue_9; cat issue_9 command (where 9 is an issue IID)
• Via glab mr view 2 --comments --system-logs > mr_2; cat mr_2 command (where 2 is an MR IID)

Screenshots (if appropriate):

Before	After

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation
• Chore (Related to CI or Packaging to platforms)
• Test gap