feat!: add backend-solvable blackboxes to brillig & unify implementations

[sirasistant]

Description

Problem*

Implements pedersen, schnorr and fixedBaseScalarMul for Brillig and resolves #402

Summary*

Context:

• Right now ACIR depends on the whole Brillig VM
• If the brillig VM depends on a solver that imports BlackBoxFunc, you get a cyclic dependency
• Also, the BlackBoxFunctionSolver trait uses OpcodeResolutionError which is ACVM specific

My proposal:

• Separate the Brillig_vm crate into a brillig crate and a brillig_vm crate (akin to acir/acvm)
  • Acir only depends on brillig crate, does not import the brillig_vm crate
  • ACVM depends on the brillig_vm crate for solving brillig opcodes
• Add a new crate blackbox_solver
  • exports functions for implementation-fixed blackboxes
  • exports BlackBoxFunctionSolver trait for backend dependant ones (will eventually be removed)
  • exports an enum BlackBoxResolutionError
  • The ACVM OpcodeResolutionError implements a From
• Modify Brillig VM to use a &BlackBoxFunctionSolver and use that for pedersen, schnorr and fixed base scalar mul
• Modify ACVM to pass the solver to the brillig VM

Additional Context

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[sirasistant]

It's a breaking change due to the change that acir now only exports brillig, not the whole brillig_vm, and the change that now BlackBoxFunctionSolver trait returns results with error type BlackBoxResolutionError instead of OpcodeResolutionError

[kevaundray]

Overall looks good to me, one nit about doc commenting the new crates