* Drone: Fix Starlark script

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

* grafana-mixin: Move build logic to scripts

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

* Drone: Use mixin scripts

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

* CI build image: Install jsonnetfmt and mixtool

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

* Makefile: Print commands

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