Use bundled typescript

[guybedford]

The issue fixed here is that the typescript loader loads typescript using a dynamic require in https://github.com/TypeStrong/ts-loader/blob/master/src/compilerSetup.ts#L15.

This is fixed using the previous dynamic require technique of allowing webpack to support a numeric require where compiler is simply the numeric require.resolve('typescript') replacement provided by Webpack.

We do this by patching the empty context module to attempt to load that numeric id when it can.

With this fixed, the remaining bug was that TypeScript loads its own types from the lib directory, but with logic that isn't statically analyzable by ncc, something like the following:

processRootFile(ts.combinePaths(defaultLibraryPath, libFileName), /*isDefaultLib*/ true, /*ignoreNoDefaultLib*/ true);

where the asset emission would work if the above was path.join(__dirname, 'lib', libFileName) but doesn't work here because we can't statically analyze either defaultLibraryPath, libFileName or ts.combinePaths.

The work-around here was just like the webpack builtins - to manually relocate the lib folder into the ncc dist folder, which surprisingly then all seems to work out ok.

It would be worth testing it further though with various configurations to be sure...

[codecov-io]

Codecov Report

Merging #138 into master will decrease coverage by 1.07%.
The diff coverage is 11.11%.

@@            Coverage Diff             @@
##           master     #138      +/-   ##
==========================================
- Coverage   74.94%   73.86%   -1.08%     
==========================================
  Files          10       10              
  Lines         455      463       +8     
==========================================
+ Hits          341      342       +1     
- Misses        114      121       +7

Impacted Files	Coverage Δ
src/loaders/ts-loader.js	0% <0%> (ø)	⬆️
src/index.js	93.15% <100%> (+0.09%)	⬆️

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