Support aliased imports

[JollyGoodHolly]

As previously seen on #9034, I would like to use a separate, TypeScript-based "commons" library in two other TypeScript projects. The problem is that aliased imports are disabled for no documented reason. A workaround is possible with react-app-rewired through react-app-rewire-alias (since version 0.1.6 also fully compatible with my problem), but this should be natively supported in CRA.

The problem this would bring is that overrides in eslint-loader does not support absolute/external paths, so either a version that does support this should be used, or it should be ignored (possibly accompanied by a warning that they are not linted).

[danielkcz]

I just wanted to use aliased imports too and it was a rather rude realization when CRA removed it from my config. Before I tried this I expected problems with Jest, but it turns out that moduleNameMapper option is no longer blacklisted which solves it. So it's surprising that CRA itself doesn't support it.

@JollyGoodHolly Thanks for the react-app-rewire-alias tip. At least some light at the end of the tunnel :)