Avoid logging large values

[eperott]

It would be nice if we could configure a size limit on values before logging them to the audit log. For instance it may not be useful to log 1M blobs into the audit log.

It should be possible to configure a size limit, and if the size of a value exceeds this limit, it should be replaced by a special character sequence. For performance reasons it would be desirable if the size could be checked before the value is extracted and escaped.

Primarily this should be implemented for prepared statements, but simple statements would be a nice bonus as well.

[etedpet]

this issue is similar/related to #126