tests/: Add t0111-filter.sh

This adds basic tests for all types of exec filters.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>

tests/filters/capitalize-argv1.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+echo "$1" | tr '[:lower:]' '[:upper:]'

tests/filters/capitalize-stdin.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+tr '[:lower:]' '[:upper:]'