wrap TextInputBuilders with ActionRowBuilders in getModal

[jr1221]

Description

This wraps the TextInputBuilder in getModal with ActionRowBuilder. I think this is better than switching getModal to take ActionRowBuilder as that would decrease readability of source code and cause frequent mistakes (people putting buttons in modals, and/or using ActionRowBuilder larger than 1 child component). If discord adds to modals getModal can be updated to allow the passing in of ActionRowBuilder.

Accompanies nyxx PR #535

Type of change

• [ X] Bug fix (non-breaking change which fixes an issue)

Checklist:

• [X] Ran dart analyze .
• [X] I have performed a self-review of my own code
• [X] I have commented my code, particularly in hard-to-understand areas
• [X] I have made corresponding changes to the documentation
• [X] I have added tests that prove my fix is effective or that my feature works