[RFC]: BuildXLScheduler

Overview

Write a thin wrapper on top of BuildXL as a "scheduler". This is a small sentence with lots of implications. So read onto the Goals to get some details. buildxl currently already has a lage frontend, however, this means that there is a slight difference in how people execute jobs with or without buildxl. The ideal is to have lage itself become a frontend to buildxl using the "custom javascript" adaptor

Goals & non-goals

Goals

1. coordinate with buildxl team to create proper Lage Frontend changes if any
2. create a BuildXLTargetScheduler that spawns a buildxl instance
3. (runtime) create a config.dsc on the fly to supply buildxl with the necessary bits to execute
4. retrieve buildxl generated cache back as a remote fallback (L3)
5. make buildxl an easy one-binary installation through a npm dependency (this is in scope, but is really a change inside buildxl's deployment)

Upstream dependencies

1. buildxl

Detailed Design

TBD!!