to keep track of runtimes, used exports depending on runtime
modules can have different hashes and generated code depending on runtime
chunks are only considered as equal for MergeDuplicateChunks and SplitChunks when exports used in contained modules are equal
added `optimization.usedExports: "global"` to opt-out from used exports analysis per runtime
added `splitChunks.usedExports` and `splitChunks.cacheGroups[x].usedExports` to enable/disable used exports comparing for modules
`splitChunks.usedExports` defaults to `true` in production
Tobias Koppers