Use Babel to resolve project root & aliases

[suzubara]

• Adds babel-plugin-module-resolver and configures the root path & sets up aliases in .babelrc
• Adds eslint-import-resolver-babel-module so eslint can resolve aliases
• Use alias imports in a few existing files to make sure it works
• Fixes Use Babel to resolve project root & aliases #1424

[suzubara]

Duplicating the config here seems to be a necessary evil due to tleunen/eslint-import-resolver-babel-module#95 (in order for eslint to properly resolve the modules). This is fixed on 5.0.0 of eslint-import-resolver-babel-module, but we're locked to ^4.0.0 because 5 requires Babel 7, and updating Babel feels outside the scope of this work.

[gidjin]

Changes look good, We are going to hold off merging this until after the sprint ends to give us more time with it locally before it goes out.

[gidjin]

Changes look good. I resolved the conflict with the other .babelrc changes. We should update the imports as we touch them in future PRs