cargo help <alias> should show what <alias> stands for #10138

Problem

Currently, if I have a .cargo/config like this:

[alias]
bw = "build --target x86_64-pc-windows-msvc --release"
bl = "build --target x86_64-unknown-linux-musl --release"

And I do cargo help bw

I get the help for cargo build

Proposed Solution

Instead of the current behavior, I would like something like git:

$ git help c
'c' is aliased to 'commit'

$ git help cam
'cam' is aliased to 'commit --amend -m'

If I want the infos for build, cargo bw --help would still work, just like git cam --help show the full help for commit in the example above.

Notes

One thing I have not seen git do is tell from where the alias comes. If possible, indicating the file (and even the precise location) would be very nice.

The same could be done for subcommands like cargo add from cargo-edit, with something like this:

$ cargo help add
`cargo add` comes from `$CARGo_HOME/bin/cargo-add`

But this could be a separate feature request, I don't know how much the two are linked internally.