databases/timescaledb: Update to 0.7.0

changelog: https://github.com/timescale/timescaledb/releases/tag/0.7.0
Moreover, switches build to CMake and adds support for pgsql10

PR: 223800
Submitted by: kbowling@freebsd.org (maintainer)
Approved by: olivier (mentor)
Differential Revision: https://reviews.freebsd.org/D13191