perf: Add transform cache, sourcemap dedupe and skip compile for js assets

[arthurfiorette]

This PR adds some main performance improvements:

1. Uses a transform cache to improve on rebuilds/watch mode.
2. Split sourcemap usage into either both or inline only to reduce memory consumption when --enable-source-maps are enabled.
3. Smartly only transform needed files instead of blindly transforming all JS/TS files.
4. Performs a fast minification of transpiled code to reduce cache I/O and size.

This PR also fixed a bug and test sourcemaps.spec.ts is now correct. From my understanding it was incorrectly testing for line 18 instead of 30.

[CLAassistant]

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