feat: allow capturing the compiler output

[yxliang01]

Currently, when we set the PYOPENCL_COMPILER_OUTPPUT=1, the compiler output can be printed to terminal. However, it's also wanted that our python script can also capture the compiler output with a built-in supported way of doing so for cases of building passing and failing.

[inducer]

Happy to consider a PR. Functionality is in pyopencl._cl.Program._get_build_logs().