Generate granular Bazel targets using module extension

It would be great if Bazel toolchains could be used to run the actual build instead of building via make/ninja.

It could work the following way:
```
# CMakeLists.txt
add_library(example_lib example.cc)

# MODULE.bazel
foreign = load("@rules_foreign_cc//extension.bzl")
foreign.cmake(
url = "https://example.com/lib.tgz",
)
use(foreign, "com_example_lib")

# BUILD
cc_library(
deps = ["@com_example_lib//example_library"]
)
```

The extension would create and execute a repository rule to [download the project](https://bazel.build/rules/lib/builtins/repository_ctx#download_and_extract) and [run CMake](https://bazel.build/rules/lib/builtins/repository_ctx#execute).

CMake would need an [additional Bazel generator](https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html) (in addition to Make/Ninja).

Start with the proposed MODULE.bazel and BUILD usage, then review the referenced extension.bzl interface and Bazel repository_ctx download_and_extract and execute APIs. Investigate the CMake generator requirements described in the issue. Done means the proposed module extension can generate granular targets and use Bazel toolchains for the actual build instead of make or ninja.

Written by the indexing model from the issue text.