Add --body alias for wl comment add/create

[rgardler-msft]

Summary: Add a --body alias for wl comment add/create that maps to the existing --comment option.

User story:

• As an agent, I want to use --body when adding comments so CLI usage is consistent with other systems and less error-prone.

Expected behavior:

• wl comment add --body "text" behaves exactly like --comment "text".
• If both --body and --comment are provided, return a clear validation error.
• Help text documents --body as an alias for --comment.

Acceptance criteria:

• Alias works for wl comment add and wl comment create.
• Help output lists --body in both commands.
• Unit tests cover alias use and conflict error.
• Backward compatibility: --comment continues to work unchanged.