rgw/test: add Journal mode support to bucket logging test suite

rgw/test: add Journal mode support to bucket logging test suite

Add --logging-type flag to run the Python bucket logging test suite
in either Standard or Journal mode. The same tests run against both
logging types with no changes to test logic or assertions.

- Add --logging-type pytest CLI option (Standard default, Journal opt-in)
- Detect boto3 LoggingType extension availability at session startup
- Thread logging_type through helpers and test functions
- Add teuthology task YAML for Journal mode suite runs
- Install service-2.sdk-extras.json in the teuthology task when
  logging_type is Journal (s3tests cleans it up after its own run,
  so the file isn't available by the time our Journal job runs)
- Document Journal mode local usage in the test suite README

Signed-off-by: Shree Jejurikar <shree.jejurikar@gmail.com>