Fix bug with webpack resolution

[jbrantly]

This addresses #92. webpack resolution was not working correctly.

From that issue:

So I've looked into this a bit and there are multiple cascading issues. The first issue is that there is a bug in ts-loader where the webpack lookup was failing (ts-loader first tries to resolve a file using webpack's resolution strategy). Since that was failing, the loader fell back on TypeScript's module resolution strategy. In this case TypeScript was unable to find the .tsx file because the jsx option was not specified in the compiler options, so that failed as well resulting in the "cannot find module" message. However, if you switched moduleResolution to node then TypeScript magically decided to include .tsx files in its lookup. Kind of weird if you ask me and possibly a bug that .tsx extension handling is done differently between the two strategies. In any case, by fixing the original bug the TypeScript resolution "bug" doesn't come into play.

The test here mimics the original issue of trying to import a tsx without specifying jsx or moduleResolution.

[jbrantly]

I was able to reproduce an issue reported in gitter and confirm that it's also resolved by this PR. Adding that scenario as an additional test. @Coderah

[Coderah]

@jbrantly Great! Thank you for remembering and informing me of this, really appreciate that.

[jbrantly]

@blakeembrey When you get a moment could you review this? (forgot to cc originally). Thanks!

[blakeembrey]

LGTM 👍