feat: add multi-target Typechain typings build option

[JDawg287]

Description

Reopening the PR that was previously reverted.

Previous PR #127

PR Checklist:

• I have performed a self-review of my code
• I have commented on my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added or updated tests that comprehensively prove my change is effective or that my feature works

[dvdplm]

The code looks fine but I have two questions:

1. Why do we want to be agnostic about the typechain? Why not be opinioated and only support ethers 6? What do we gain from being flexible here?

2. Reading thew (great!) docs about how to pass in the preferred typechain, I'd like to know what the priority rules are. Env var is trumped by CLI arg? Both trumped by config file? The downside of great flexibility is that we now must test&document all the permutations. Is the flexibility worth it?

[JDawg287]

To answer the following question:

2. Reading thew (great!) docs about how to pass in the preferred typechain, I'd like to know what the priority rules are. Env var is trumped by CLI arg? Both trumped by config file? The downside of great flexibility is that we now must test&document all the permutations. Is the flexibility worth it?

I did light testing on my part with all the scenarios. As for the priorities I set up the following:

    const typechainTarget =
      args.typechainTarget ||
      process.env.TYPECHAIN_TARGET ||
      hre.config.typechain.target // default 'ethers-v6'

The command line argument is the highest priority and overrides the rest since it is straightforward.
If there are no command line arguments but an environment variable is present instead, we take the value from there.
If either of them is not present then the value defaults to the hardcoded value in the config file.
Shouldn't be that complicated here.

As for the first question, @sebastiendan might be able to answer that with more detail.

[sebastiendan]

As for the first question, @sebastiendan might be able to answer that with more detail.

@dvdplm This is related to topos-js and its unbiased architecture (potentially usable with any evm chain client, with any graphql client, etc.)