Replace Bootstrap-sass with Bootstrap gem (Bootstrap 3 to Bootstrap 5)

[yuenmichelle1]

As mentioned here: #1669
If we ever want to move to Rails 8 and utilize propshaft + dartsass-rails, we will need to move away from bootstrap-sass

[yuenmichelle1]

Reference image of what app looks like when you drop in and replace bootstrap-sass (gem) with bootstrap gem (Bootstrap 5)

cc @lcjohnso

[yuenmichelle1]

Implementation notes:

• Michelle's attempt to fix lives on branch asset-pipeline-2 (this fix does not include propshaft + dartsass-rails).
• I believe we could do this more gradually, going from bootstrap-sass (BS3) to BS4 using bootstrap gem v 4.5.3 https://github.com/twbs/bootstrap-rubygem/tree/4.5-stable; but I have not tried this out yet.

[yuenmichelle1]

Accidentally closed while typing implementation notes **