Slf4jFormatShouldBeConst: tolerate use of simple LOGGER.info(String)

[gregallen]

This is bad and deserves to be raised as error:

1. logger.info("blah: " + var);

However, this is sometime tolerable:

2. logger.info(computeToString(var))

Since the log methods which take no arguments short-cut all the format logic and varargs array creation etc - e.g. see org.slf4j.helpers.MessageFormatter#arrayFormat(java.lang.String, java.lang.Object[], java.lang.Throwable)
Note in particular that with this single argument call slf4j does not parse the passed string for {} placeholders

Hence replacing with this has non-trivial performance impact

logger.info("{}", computeToString(var))

Hence it would be useful if (2) could either be captured by a different check, or permitted