Add project-reference-based webpack bundling

[mitchhentgesspotify]

ts-project-references is similar to ts-transpile in that it uses webpack, ts-loader and typescript, except that it can reuse already-built typescript code.

Unfortunately, ts-loader and typescript don't allow using project references while also only transpiling at the same time. So, when bundling with ts-project-references, it's doing a full, slow type-checking compile.

However, its reuse of clean (unmodified), already-compiled sub-projects is slightly faster (per-sub-project) than having to transpile from scratch.

This means that in a sufficiently large composite project, making a change to a single sub-project and re-bundling is faster with ts-project-references than ts-transpile.
Additionally, as a side benefit, this reuse applies to the output from regular tsc --build runs, so "linting" the full repo also preps it for a faster bundle as well.

However, first time builds become far slower.

Here's some results from a single round of testing:

*** FIRST BUNDLE TIME ***
bundleTs                  | avg=39617ms stdev=0
bundleTsProjectReferences | avg=184977ms stdev=0
bundleSucrase             | avg=12786ms stdev=0
bundleEsbuild             | avg=10725ms stdev=0
bundleBabel               | avg=41364ms stdev=0

*** INCREMENTAL BUNDLE TIMES ***
bundleTs                  | avg=39513ms stdev=0
bundleTsProjectReferences | avg=32015ms stdev=0
bundleSucrase             | avg=13154ms stdev=0
bundleEsbuild             | avg=11397ms stdev=0
bundleBabel               | avg=40877ms stdev=0

[mitchhentgesspotify]

This PR depends on #28.

[mitchhentgesspotify]

Weirdly, in the incremental bundle-ts-project-references, less than a second is spent compiling typescript code. So, ~30s is spent in webpack bundling. Next, I'll see how esbuild performs with Typescript Project References.

[mitchhentgesspotify]

Next, I'll see how esbuild performs with Typescript Project References.

Hmm, since esbuild is transpiling typescript itself (it's not running tsc under-the-hood), it can't (and, doesn't really need) the performance benefits of project references, and therefore doesn't support it.

The way to "add" project-reference support to esbuild is with this plugin, but that's essentially just so the esbuild transpiler implementation can resolve the same file references that regular tsc can, it doesn't gain the same kind of "re-use the compiled output" benefits that tsc does - but, again, at its performance level it doesn't really need them either.