Add vmodule support to TF OSS logging.

Setting the environment variable TF_CPP_VMODULE=foo=7,bar=7 will cause the
"foo" and "bar" translation units (foo.{h.cc},bar.{h.cc}) to have a VLOG level
of 7, meaning VLOG(0) to VLOG(7) in those translation units will be logged to
stderr (as LOG(ERROR) does).

Previous:

Benchmark         Time(ns) Iterations
-------------------------------------
BM_DisabledVlog          3  215821571

Lambda:

Benchmark         Time(ns) Iterations
-------------------------------------
BM_DisabledVlog          3  247013779

So change for disabled VLOGs seems in the noise
in the microbenchmark.

PiperOrigin-RevId: 163995038