Use .dylib extension for macOS dynamic libraries in Unix toolchain
Use .dylib extension for macOS dynamic libraries in Unix toolchain

The autoconfigured Unix toolchain previously did not set any artifact_name_patterns, which meant that all artifacts used the default(Linux) patterns. This was incorrect in the case of dynamic libraries on macOS, which should have the extension `.dylib` rather than `.so`.

Fixes #11082.

Closes #14158.

PiperOrigin-RevId: 413363126

bazelbuild/bazel,cushon/bazel,bazelbuild/bazel,cushon/bazel,bazelbuild/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,cushon/bazel,bazelbuild/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,cushon/bazel,cushon/bazel,katre/bazel,katre/bazel,katre/bazel,ButterflyNetwork/bazel,katre/bazel,ButterflyNetwork/bazel,ButterflyNetwork/bazel,cushon/bazel,katre/bazel,ButterflyNetwork/bazel,katre/bazel