control installing of Rust packages

[PetrKralCZ]

• For installing software written in Rust we are using the cargo install command. This command downloads all the latest dependencies.
• We need to have full control over the versions of dependencies being downloaded and ideally let EasyBuild download them itself and install them from local directories.
• The problem is, it seems the cargo command always expects there is a Cargo.toml file specifying these dependencies.
• The cargo install <dependency_name> only works for installing programs and not libraries.

error: there is nothing to install in `anyhow v1.0.68`, because it has no binaries
`cargo install` is only for installing programs, and can't be used with libraries.
To use a library crate, add it as a dependency in a Cargo project instead.

• The cargo fetch command also expects a Cargo.toml file

error: could not find `Cargo.toml` in `/home/user` or any parent directory

• The fact that there is a --offline option for the cargo install and the cargo vendor command suggests there should be a way to install dependencies from a local directory.
• Otherwise the ext_list of Rust-written dependencies would probably need to be used to generate a custom Cargo.toml file.

[boegel]

Hmm, maybe it would be better to have an issue for this in the EasyBuild GitHub repository, since this is not exactly specific to VSC...

Thoughts @smoors, @lexming?

[boegel]

easybuilders/easybuild-easyblocks#2902 looks like an interesting start?

[boegel]

closing this since easybuilders/easybuild-easyblocks#2902 was merged and included in EasyBuild v4.7.2