Add a command-line option to suppress the IRB startup banner

[elfham]

In #1183, a feature was added that displays a banner when IRB starts.

However, there are cases where avoiding extra output is desirable, so I would like to request a command-line option to suppress these messages.

For example, Python provides a "quiet mode" with python -q:

% python3
Python 3.11.15 (main, Mar  5 2026, 01:05:40) [Clang 19.1.7 (https://github.com/llvm/llvm-project.git llvmorg-19.1.7-0-gcd7080 on freebsd15
Type "help", "copyright", "credits" or "license" for more information.
>>> exit()
% python3 -q
>>> exit()
%

It would be helpful if IRB also had an option such as --nobanner to suppress the startup banner.

The actual option name is, of course, up to the maintainers; the examples above are just suggestions.

Thank you for your consideration.