add integration test for in-array writing

Author: jberthold

kmir/src/tests/integration/data/exec-smir/arrays/array_write.rs

@@ -0,0 +1,12 @@
+fn main() {
+
+    let mut a: [i16; 4] = [1;4];
+
+    a[0] = 2;
+
+    let b = &mut (a[1]);
+
+    *b = 2;
+
+    assert!(a[0] == a[1]);
+}