* First pass at adding comment trees.

- Extracted comment replies into its own table.
- Added ltree column to comment
- Added parent_id param to GetComments to fetch a tree branch
- No paging / limiting yet

* Adding child_count to comment_aggregates.

* Adding parent comment update counts

* Fix unit tests.

* Comment tree paging mostly done.

* Fix clippy

* Fix drone tests wrong postgres version.

* Fix unit tests.

* Add back in delete in unit test.

* Add postgres upgrade script.

* Fixing some PR comments.

* Move update ltree into Comment::create

* Updating based on comments.

* Fix send soft fail.