Benchmark macro compile times

[neko-kai]

It seems like Scala 3 projects using distage macros / izumi-reflect macros compile slower than Scala 2 versions of the same. To get at the root of the issue we need to find if there was a performance regression in library macros - or the cause is in compiler itself / other libraries.

NB: We can use https://github.com/MateuszKubuszok/derivation-benchmarks as a scaffold for compiler benchmarking

NB2: https://github.com/7mind/distage-example is one of the projects that exhibits a slowdown in compile time on Scala 3. It may be used as a first target for benchmarking / investigation.

[neko-kai]

Seems like distage-extension-config macros are unusually slow compared to Scala 2 version. Scala 2 version used pureconfig-magnolia, but Scala 3 version uses custom inline code based on slow Mirror – it should be rewritten into a single-pass macro instead, possibly using a Scala 3 alternative to magnolia such as oxygen-meta.