SI-7331 tb.parse returns unpositioned trees

This pull request gets rid off code wrapping that was previously used by toolbox to get into correct parsing mode. Instead combination of templateStats/accept(EOF) is used. This is the same solution as the one used in repl and built-in scriptRunner

This pull request doesn't attempt to generalize this approach in any way and re-use it all over the place due to the caution of accidental compatibility breakage. I plan to do it separately against master.

Additionally there are a few more changes that make importers be aware of positions and a test for that (via @jedesah).