fix(release 0.3.0: rewrite FsBlockStore.list; crate compiles as dependency again

[Christian7573]

This PR rewrites FsBlockStore.list using for and while let loops, which removes a compilation error when using the ipfs crate as a dependency from another project. See issue #458 for relevant discussion.

Checklist (can be deleted from PR description once items are checked)

• New code is “linted” i.e. code formatting via rustfmt and language idioms via clippy
• There are no extraneous changes like formatting, line reordering, etc. Keep the patch sizes small!
• There are functional and/or unit tests written, and they are passing
• There is suitable documentation. In our case, this means:
  • Each command has a usage example and API specification
  • Rustdoc tests are passing on all code-level comments
  • Differences between Rust’s IPFS implementation and the Go or JS implementations are explained - N/A?
• Additions to CHANGELOG.md files

[koivunej]

There are few fmt issues and I guess clippy as well. Sorry about that.

[koivunej]

It seems that there's something wrong with vcpkg.. Trying to find time to look into this.

[koivunej]

I got closer to the issue in #470 and deduced it was caused by a trouble inferring the two lifetimes generated by async-trait seen here in the expansion of the original code (with some tracing parts removed). Moving the method body as FsBlockStore::list0 outside the #[async_trait] impl BlockStore for FsBlockStore { ... } and just calling the new method in the BlockStore::list implementation worked around the issue.

I would prefer to keep the current "less buffering" version if possible, even if there's no concurrent execution of the streams. Could you peek at #470 and see if it matches your understanding of the compilation failure?

[Christian7573]

#470 works for me. Awesome!