Update labeler and codeowner configs for CMake files (#15208)

When working on #15206, I noticed the `rapids_config.cmake` file was not properly labeled. Based on offline discussions, we also noticed that the file's codeowner was misconfigured as well.

This PR updates both github `labeler` and `CODEOWNER` files to properly handle files with `.cmake` extension.

Authors:
  - Yunsong Wang (https://github.com/PointKernel)

Approvers:
  - Bradley Dice (https://github.com/bdice)
  - Ray Douglass (https://github.com/raydouglass)

URL: #15208

.github/CODEOWNERS

@@ -11,6 +11,7 @@ python/dask_cudf/  @rapidsai/cudf-dask-codeowners
 cpp/CMakeLists.txt               @rapidsai/cudf-cmake-codeowners
 cpp/libcudf_kafka/CMakeLists.txt @rapidsai/cudf-cmake-codeowners
 **/cmake/                        @rapidsai/cudf-cmake-codeowners
+*.cmake                          @rapidsai/cudf-cmake-codeowners
 
 #java code owners
 java/              @rapidsai/cudf-java-codeowners

.github/labeler.yml

@@ -10,6 +10,7 @@ libcudf:
 CMake:
   - '**/CMakeLists.txt'
   - '**/cmake/**'
+  - '**/*.cmake'
 
 cuDF (Java):
   - 'java/**'