Migrate deprecated buttons to Pajamas components

What does this MR do and why?

Migrate deprecated buttons to Pajamas components

This MR is for Pajamas Migration Day.

I tried to tackle each of the issues in diff_helper.rb, but the migration of the inline/side-by-side toggle would be best handled with a new Vue component as there is no direct migration path for it. That's a little beyond my capacity (both in terms of time and ability) in this milestone.

Related issue: #417798 (closed)

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