feat: allow specifying binary aliases / links

[mistydemeo]

This adds support for binary aliases. Developers whose package installs a binary under one name can specify one or more aliases for any of their binaries, and those aliases will be produced by the installers alongside the actual binary. On Linux and macOS, this uses symbolic links; the shell installer simply runs ln -s, while the Homebrew installer uses Homebrew's native "symlink under another name" syntax. On Windows, we use hardlinks due limitations with symlinks discussed in #961.

The syntax used for this in Cargo.toml is broadly similar to what we use for runners:

[workspace.metadata.dist.aliases]
akextract = ["akextract-link"]
akmetadata = ["akmetadata-link1", "akmetadata-link2"]

Fixes #961.

[mistydemeo]

Tested in my cargodisttest repo: https://github.com/mistydemeo/cargodisttest/releases/tag/v0.2.122

I've tested with shell, Homebrew, and powershell installers.

[Gankra]

Wants a bit more logic up in rust land, I think.

[Gankra]

As discussed last week, we should probably prioritize folding these kinds of things into more existing tests rather than adding more and more (both because it makes the diff actually useful, and because these take forever to run).

[mistydemeo]

Yeah, I agree. Can we do that in a followup, though? I'd like reorganizing our tests to be fairly intentional, which means we can think directly about which tests contain which groups of features instead of it being a byproduct of this PR.

[ashleygwilliams]

@mistydemeo a follow up seems good to me- can you file an issue?

[mistydemeo]

Done: #979