dev: allow specify start.sh only and except via envvar
Created by: keegancsmith
This allows me to always run with the same environment via direnv. For example this is my setup to do docker free development :)
# Kill docker in dev with fire
export CTAGS_COMMAND=/Users/keegan/src/github.com/universal-ctags/ctags/ctags
export USE_SYNTECT_SERVER_FROM_PATH=t
export SRC_DEV_EXCEPT=grafana,prometheus,postgres_exporter