Index span.db.statement as text

The db statement is really useful, but it would be even more amazingly useful if we could search on it.

So by adding this mapping:


We should be able to search for spans which have a certain db query structure.


One gotcha I seem to be hitting in this test is that I can't search for `jvm` or `heap` . Seems like maybe I'm catching an "ignore_above" but I didn't think they were supposed to kick in on text fields.

Either way, I imagine it'd be quite useful to do things like highlight traces that involved specific query structures (indices, tables, etc).