Internal improvement: Update compile interface

[eggplantzzz]

This PR changes a couple of interfaces in Truffle:

First, it aims to standardize and interface for compilation packages. They all now export a Compile object which has an all and necessary method which is required to use with workflow-compile.

compile-solidity, compile-vyper, and external-compile now return a CompilerResult which is an array of Compilations. (see the new types in compile-common) Currently they all still only return 1 compilation per package but in the future we plan to potentially return multiple compilations per package. This would be especially helpful when, for example, we might need to use multiple versions of the Solidity compiler for a set of contracts.

Second, it changes the return from workflow-compile (WorkflowCompileResult). It now returns an object with contracts and compilations.

In addition to the above, it also begins moving some shimming logic to compile-common.

🛠️ NOTE: This is a breaking change for compile-solidity, workflow-compile, compile-vyper, and external-compile.

[gnidan]

Here's a round of changes to the types!

Just looked over this at large and it's nice how it's taking shape!

[gnidan]

Here we go!