[FR] create a sample showing how to use sccache

### Description

It's actually trivially easy to use sccache with CMake:

```
find_program(SCCACHE_PATH sccache REQUIRED)
set(CMAKE_C_COMPILER_LAUNCHER "${SCCACHE_PATH}")
set(CMAKE_C_LINKER_LAUNCHER "${SCCACHE_PATH}")
set(CMAKE_CXX_COMPILER_LAUNCHER "${SCCACHE_PATH}")
set(CMAKE_CXX_LINKER_LAUNCHER "${SCCACHE_PATH}")
```

Might be worthwhile to build a full sample that does that with a GCS bucket for caching a github action.

Use the CMake snippet in the issue as the starting point, then identify where a complete sample and GitHub Actions workflow belong in the NDK repository. The sample should demonstrate sccache with C and C++ compiler and linker launchers, while the workflow uses a GCS bucket for caching. Confirm the result by running the sample build and workflow.

Written by the indexing model from the issue text.