FIR IDE: move low level api testdata sources to the analysis directory

analysis/low-level-api-fir/testdata/getOrBuildFir/expressions/forExpression.kt

@@ -0,0 +1,7 @@
+fun foo() {
+    <expr>
+    for (x in 0..1) {
+
+    }
+    </expr>
+}