Feat: Create print_github_reviews.py script and add features

This commit culminates a series of enhancements to create a standalone script
for printing GitHub pull request review information.

Key changes from the original `get_pr_review_comments.py` and subsequent iterations include:

- Renamed script to `scripts/print_github_reviews.py` (from `scripts/gha/get_pr_review_comments_standalone.py`).
- Made script standalone by inlining necessary GitHub API interaction functions.
- Auto-detection of repository owner/name from git remote.
- Auto-detection of PR number from the current git branch if not specified.
- Added support for fetching and displaying top-level PR review summaries (e.g., Approve, Comment, Changes Requested) in addition to line comments.
  - Top-level reviews are filtered for 'DISMISSED' state and by `--since` timestamp.
  - Empty-bodied 'COMMENTED' top-level reviews are also filtered out.
- Enhanced the 'next command' suggestion to use the latest timestamp from either overall reviews or line comments.
- Numerous bug fixes and refinements to argument parsing, error handling, and output formatting:
  - Resolved `UnboundLocalError` for timestamp tracking.
  - Addressed `argparse` conflict for `--pull_number`.
  - Removed deprecated nested argument groups.
  - Standardized error messages to be more concise and suggest `--help`.
  - Conditional printing of section headers.
  - Default logging verbosity set to WARNING.
  - Removed extraneous comments.

Author: google-labs-jules[bot]

scripts/gha/get_pr_review_comments_standalone.py renamed to scripts/print_github_reviews.py

@@ -485,9 +485,10 @@ def parse_repo_url(url_string):
     # Handling for empty line comments will be just before their processing loop.
     # if not comments: (handled later)
 
+    # Initialize timestamps for 'next command' suggestion
     latest_overall_review_activity_dt = None
-    latest_line_comment_activity_dt = None # Renamed from latest_activity_timestamp_obj
-    processed_comments_count = 0 # This tracks line comments
+    latest_line_comment_activity_dt = None
+    processed_comments_count = 0
 
     # Only print line comments header if there are comments to process
     # The 'comments' list here has already been checked for None (API error)