Add S3 logging to TensorFlow's logging system (#15493)

* Add S3 logging to TensorFlow's logging system

This fix is an attempt to help the issue raised in 15159
where there is no logging in S3 file system and it is not easy
to debug to diagnose.

This fix adds S3 logging to TensFlow's logging with
```
LogLevel::Info -> INFO
LogLevel::Warn -> WARNING
LogLevel::Error -> ERROR
LogLevel::Fatal -> FATAL
```

This fix is related to 15159 (not a complete fix).

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Sanitize with clang-format

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Enable S3 logging to TensorFlow logging

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Sanitize with clang-format

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Update Bazel BUILD file

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Address review feedbacks.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* const local variable

* Make local variable const and avoid std::string

* Add punctuation & remove redundant comment

* Expose  InitializeAWSLogging and ShutdownAWSLogging in S3Logging

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Fix style.

* move static functions first
* move member functions before members fields
* see if DISALLOW_COPY_AND_ASSIGN will work.

* Update `S3Log` => `AWSLog` for review feedback

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Set TF_CPP_MIN_LOG_LEVEL=1 to filter out LOG(INFO)

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>