feat: add a `resolved` target to local binary repositories
This removes the need for a custom resolved
rule for every toolchain.
Upgrade path is to add the toolchain_type
to the local repository
rule in MODULE.bazel
and change the resolved
target to an alias.
A toolchain_resolved
repository rule is added as well for toolchains
that do not use local binaries.
This patch hugely simplifies the creation of toolchains downstream.