Set p5.js v2 to Default

[raclim]

Changes:

• Updates Banner Copy to reflect p5.js v2 default and provide links to transition guide.
• Sets p5.js v2 to default in version dropdown, and add "Default" and "Not Maintained" labels. Also updates copy in Preferences modal.

Fixes #4149

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• has no typecheck errors (npm run typecheck)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123
• meets the standards outlined in the accessibility guidelines