Make test execution not take quadratic compilation time (#7610)

* make test execution not take quadratic compilation time

* add -p flag. we can only test one package at a time (for now)

* cd to mattermost-server for enterprise

* whoops

* let's go ahead and make the coverage profiles ready for concurrent test

scripts/test-xprog.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+set -e
+[[ $1 =~ (github.com.*)/_test ]] && \
+    echo Testing ${BASH_REMATCH[1]}
+coverprofile=`pwd`/cprofile.out
+if [[ $1 == *"/enterprise/"* ]]; then
+    cd "$(dirname "$(dirname "${BASH_SOURCE[0]}")")"
+fi
+"$@" -test.coverprofile "$coverprofile"