Feature/ember4.12

[veelci]

Update from Ember 3.28 to Ember 4.12

Things to note:

• I did the upgrade in 3 stages, 3.28 to 4.4, 4.4 to 4.8, and 4.8 to 4.12
• I added the test styles to .stylelintignore since the minified boostrap styles were triggering linting errors
• The project appears to use yarn, but useYarn: true is not present in the ember-try config
• formatters.formatZipcode(94606) returns a number instead of a string
• There was a pretty large merge conflict in ci.yml, so that will probably need to be looked at (though I think I remember CI failing after the last PR)

[veelci]

Closing due to #44