[Event Request] Event for string table statistics

This could be emitted as a requestable event, and by default only be emitted every chunk.

There could be one event event type for the SymbolTable and one for the StringTable.

The events could have the following attributes:
* Number of buckets
* Number of entries
* Number of literals
* Total footprint
* Average bucket size
* Std dev of bucket size
* Max bucket size