Add support for using custom cargo metadata when in a workspace

[jessebraham]

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Alright, let's try this again 😁

I took the advice of @liebman and used cargo in place of the cargo_toml package, and this has resulted in a much more robust and flexible solution. Not entirely happy with the load_metadata function still, but it appears to work at least.

I did actually test this on hardware this time around, and it seems to be working as intended. @liebman if you could test this out one more time that would be appreciated!

Also cleaned up the errors module, bumped a couple dependencies, and some other little bits.

(Hopefully) closes #291

[liebman]

Using a small test project I tested running at the projects root and in the binary crates directory.

I found that this needs to use a newer cargo than 0.63 or it does not have support for workspace inheritance and you get this

Error: cargo_espflash::invalid_workspace

  × The current workspace is invalid, and could not be loaded
  help: Ensure that a valid Cargo.toml file is in the executing directory

If I update it to 0.66 (latest) it works well. With one minor issue.

• Running from root works well (with .cargo/config.tom at workspace root level)
• Running from the binary crate fails if there is no .cargo/config.toml in the current directory as it can't find the target (it does not look in the workspace root directory)

Basically there currently has to be a .cargo/config.toml in the current directory to specify a target. Ideally it would look first in the package that will be flashed (--package option if running from root) and if one is not found there then the workspace root.

I see you have a comment about having to use an older version - would not that only apply if these were going to be run on an esp32 target?

[jessebraham]

Sorry for the delays, I needed a little break from this project 😅

Thank you for providing the example project. I have made a number of additional changes and I am able to flash your project both from the workspace root and from within the candle package, so I think we're in good shape! @liebman if you wouldn't mind just giving this one more test to verify it's working on your end that would be appreciated!

EDIT: Oops, cargo is unhappy about our MSRV. Will fix.

[liebman]

This works!