* Core: use go-datemath in time_range

* Core: update timerange for negative epoch

* Core: update gtime component

* Core: clean up time_range tests

* Update pkg/components/gtime/gtime.go

Co-Authored-By: Arve Knudsen <arve.knudsen@gmail.com>

* Core: clean gtime tests

* components/gtime: Fix test

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>