cargo registry - respect renamed dependencies

[usbalbin]

rust allows renaming dependencies such as when depending on multiple versions of the same package. This is not supported by gitea as discovered in #31500 . This PR tries to address that.

Not yet tested

[usbalbin]

This is my first PR to gitea and first ever two lines of go code so please keep that in mind :)

From what I can tell there is some sort of testing machinery in tests/integration/api_packages_cargo_test.go . Should I update that to test this?

[delvh]

Looks fine to me, but I'm not certain if that is doing everything it should.
It's probably best if @KN4CK3R looks at it as well.

[usbalbin]

The links i used:
API :
publish

{
    [...]
    "deps": [
        {
            // Name of the dependency.
            // If the dependency is renamed from the original package name,
            // this is the original name. The new package name is stored in
            // the `explicit_name_in_toml` field.
            "name": "rand",
            [...]
            // If the dependency is renamed, this is a string of the new
            // package name. If not specified or null, this dependency is not
            // renamed.
            "explicit_name_in_toml": null,
        }
    ],
    [...]
}

Registry index
JSON schema

[...]
"deps": [
        {
            // Name of the dependency.
            // If the dependency is renamed from the original package name,
            // this is the new name. The original package name is stored in
            // the `package` field.
            "name": "rand",
            [...]
            // If the dependency is renamed, this is a string of the actual
            // package name. If not specified or null, this dependency is not
            // renamed.
            "package": null,
    }
    [...]
}

[usbalbin]

This should probably default to dep.Name if dep.ExplicitNameInToml is not set

[lunny]

It's better to have a test for that.