Clean up terms used for issues. Use New instead of Add.

What does this MR do?

Clean up terms used for issues. Use New instead of Add.

Why was this MR needed?

The UX guide pointed to using Add issue instead of New issue.

Does this MR meet the acceptance criteria?

• Documentation created/updated
• Tests
  • All builds are passing
• Branch has no merge conflicts with master (if it does - rebase it please)