Build many functions using a single build script

[mrgrain]

Is your feature request related to a problem? Please describe.

esbuild is super fast and can build multiple entrypoints at the same time. In a multi lambda setup, it could be used to build and bundle multiple functions in one go, as along as they use the same settings

Describe the solution you'd like

Some class that allows to combine many assets into a one asset and bundle command.