rules_uv and cc toolchain

Hey all,

I want to use `create_venv` to built a virtual environment which includes `python-ldap`.
`python-ldap` does *not* ship wheels, bindings must be compiled from source during installation (see https://www.python-ldap.org/en/python-ldap-3.4.3/installing.html).

With `rules_uv`, building a venv would fallback to searching for `clang` and fail during `bazel run`:
```
bazel run //:create_venv
....
creating build/temp.linux-x86_64-cpython-312/Modules
clang -pthread -fno-strict-overflow -Wsign-compare -Wunreachable-code -DNDEBUG -g -O3 -Wall -fPIC -fPIC -DHAVE_SASL -DHAVE_TLS -DLDAPMODULE_VERSION=3.4.3 "-DLDAPMODULE_AUTHOR=python-ldap project" "-DLDAPMODULE_LICENSE=Python style" -IModules -I/home/timotheus/.cache/uv/builds-v0/.tmpI2PFRO/include -I/home/timotheus/.cache/bazel/_bazel_timotheus/8eab503e08f341c0f5040098b6ae80b5/external/rules_python~~python~python_3_12_3_x86_64-unknown-linux-gnu/include/python3.12 -c Modules/LDAPObject.c -o build/temp.linux-x86_64-cpython-312/Modules/LDAPObject.o

[stderr]
/home/timotheus/.cache/uv/builds-v0/.tmpI2PFRO/lib/python3.12/site-packages/setuptools/_distutils/dist.py:261: UserWarning: Unknown distribution option: 'test_suite'
warnings.warn(msg)
no previously-included directories found matching 'Doc/.build'
error: command 'clang' failed: No such file or directory
```

In our project, we already have a `cc` toolchain registered via `rules_cc`.
Is it possible to tell `rules_uv` to use that toolchain instead of searching for `clang`?

Regards
Timi

Start by reading how rules_uv's create_venv invokes builds for source-only Python packages, then compare that with the project's existing rules_cc toolchain registration. Verify the behavior with the python-ldap installation scenario shown in the issue; done means bazel run can build the package using the registered cc toolchain instead of searching for clang.

Written by the indexing model from the issue text.