test: namespace cleanup, common -> src, tenv -> lib, etc.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

test/lib/enter.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+
+set -eu
+
+cmd=""
+if [ "$#" -lt 1 ]; then
+	cmd="/bin/sh"
+else
+	cmd=$1
+	shift
+fi
+
+TEST_DIR=$(dirname "$0")/..
+SYSROOT="${SYSROOT:-$(pwd)/${TEST_DIR}/sysroot}"
+PID_FILE="$SYSROOT/running_test.pid"
+
+if [ -f  "$PID_FILE" ] ; then
+	target=$(cat "$PID_FILE")
+	target=$(pgrep -P "$target")
+else
+	echo "No test running!"
+	exit 1
+fi
+
+# shellcheck disable=SC1091
+. "$TEST_DIR/test.env"
+
+"$(dirname "$0")"/exec.sh "$target" "$cmd" "$@"