Adds Time on Page metric to Top Pages report (#1007)

* First pass

Needs more testing & potentially cleanup

* Fixes tests, error handling

* Formatting

* Removes broken test

* Fixes inconsistent test

This was due to Clickhouse setup not inserting the sessions with the exact same timestamp consistently and making the test inconsistent

* Combines `include` param, asyncs time_on_page and bounce_rate

* Fixes CH error when no pageviews exist in period

* Format

* Changelog

* Increases await timeout to accomodate larger data sets

* Improves handling of timeout behavior

* Fixes session-based filtering on time on page queries

* Formatting

* Removes old forced entry page modal from top pages report