[golemfactory/golem] Marketplace implementation stub in Rust (#3202)

This is my proposal for integrating Rust into Golem and it’s supposed to be an RFC, I’m not married to any approach used here.

Please disregards the `pick_provider` implementation as it’s not relevant at all and only demonstrates the idea.

And the idea is that, there’s gonna be one rust library which all the public API exported in `rust/golem/src/lib.rs`. This is the only file that will take care of converting to/from Python/Rust.
The Rust code itself will be modularized and able to share common code. It will have extensive coverage of unit tests as usual for libraries.

Then in certain places in Golem core we will just import relevant pieces of the Rust library. And these will be covered with very simple integration test(s) (I’d expect usually just a single one) to check whether the Python/Rust conversions are correct.
You can view, comment on, or merge this pull request online at:

https://github.com/golemfactory/golem/pull/3202

— Commit Summary —

* Marketplace implementation stub in Rust

— File Changes —

M .gitignore (8)
A golem/marketplace/__init__.py (1)
A rust/golem/Cargo.toml (12)
A rust/golem/src/lib.rs (21)
A rust/golem/src/marketplace.rs (18)
M setup.py (8)
A tests/golem/marketplace/test_marketplace.py (5)

— Patch Links —

https://github.com/golemfactory/golem/pull/3202.patch
https://github.com/golemfactory/golem/pull/3202.diff