Adapt solver-service for ocaml-ci and ocaml-docs-CI

[moyodiallo]

This is the steps.

• Upgrading solver-service to ocaml-ci one.
  • the solver in solver-service is from ocaml-ci solver at some point. The last code of ocaml-ci's solver don't change much.
• Adapt the protocole of solver-service for more opam-repository.
• Split schema.capnp file to 2 two file solve.capnp and build.capnp
• Connect ocaml-multicore-ci using the protocol from solver-service-api library (vendored). Vendoring solver service ocaml-multicore-ci#37
• Connect ocaml-ci to submit solves Vendoring solver service ocaml-ci#634

[tmcgilchrist]

• Application and Operational Metrics for solver as a service Application and Operational Metrics #57
• Support ocaml-docs-ci solving requests Use the solver pool ocaml-docs-ci#86
• Return current solver machine (toxis) to general ocluster usage https://github.com/tarides/infrastructure/issues/29 Toxis is dead!
• Deploy solver-worker to linux-arm64 machine
• Extend solver to support multiple opam-repository checkouts Discussion around the improvement of solver-service #53 Initial OCaml 5 / Eio port #71
• Extend solver requests to include caching hints, similar to build jobs, so that repeated solves re-use the same machine. Implies scaling solver pool to > 1 machine
• Investigate ways of splitting and canonicalising dependencies to improve sharing of cached results See patrick's comment.