[REPO] build basic tooling: core dependencies switch

[jmday]

As a networking developer, I can rely on basic tooling for dev work so that I don't get annoyed with wasting time doing mundane things over and over (and over).

• SPIKE: Easily switch core dependencies back and forth between crates.io and local path refs
  • (… would be nice if we had Named custom cargo profiles rust-lang/rfcs#2678)

[neonphog]

https://hackmd.io/eGD2oR6ZSLCBJa7e_uWvPA

[neonphog]

Waiting on review: holochain/holochain-rust#1442

[neonphog]

recommendation documented. Please see https://github.com/holochain/holochain-rust/blob/develop/doc/dependency_dev_pattern.md for procedure.