[Spike] Research scope of updating React-Bootstrap to v5

[grahamlangford]

Motivation

• We hypothesize that upgrading would simplify theming
• Find out the basic LOE for the upgrade
• We should consider how this impacts the Form Builder

Notes

• Timebox to 2-4 hours

[grahamlangford]

@mnholtz please add any other context as you see fit

[github-actions]

This issue will be closed in 7 days unless the stale label is removed, or a comment is added to the issue.

[mnholtz]

After upgrading to Bootstrap 5 in the www project, I identified that migrating over utility classes is trivial, but verifying visual regression is non-trivial. I still think this will be valuable to look into (and will keep this on my 30% time radar) due to deprecations in sass 1.80.0 which I'm not sure if Bootstrap 4 will support (we'll have to keep an eye on that). See this ticket here: https://github.com/pixiebrix/pixiebrix-www/pull/1122