* Hopefully the updated name should be more clear that we are inhering
some existing cargo artifacts and NOT inheriting something like
CARGO_BUILD_TARGET which refers to the host target being built
* This should make it a bit easier to tell at a glance what inputs are
significant for the derivation without having to look at the entire
source (and corresponding hooks)
* The intention is to make it more clear that this flag controls copying
the target directory so that *other* derivations can use it, and DOES
NOT control whether we use an *existing* target directory from another
derivation
* If the source root contains a Cargo.lock file it will be used to
create a vendor directory
* Otherwise a (descriptive) error will be thrown describing how to
remediate
* The caller can, of course, manually specify their own `cargoVendorDir`
which will skip the default vendoring
* We can simplify the configuration by removing the
`doCopyTargetToSeparateOutput` parameter
* If a caller wants to copy target artifacts into any other output, it
is pretty trivial for them to add their own logic for it
