Log additional in-flight transaction metadata

The current process for the LogMiner buffered implementation is to log entries like the following at DEBUG level if there are any cached transactions that haven't yet rolled back or committed.
```
XID1 (SCN), XID2 (SCN), ...
```
The `Transaction` manages other metadata such as creation time and number of events. It would be helpful for administrators to have this information so they can make a better-informed decision about dropping a transaction without having to rely on manual LogMiner queries.

In addition, when using the deferred transaction configuration, it would also be helpful to include the state of the deferred transaction map in this logged output. A deferred transaction carries similar information, so having a second log entry for deferred transactions would easily work with the same logged setup.