Add indexed key support to --state-values-set (#1042)

Adds support for indexed key arguments and escaped dot arguments to `--state-values-set`.
Things like `--state-values-set config\.yml.something=abc` or `--state-values-set config.something[0]=abc` can be passed in the command line.

Resolves #899

pkg/maputil/maputil_test.go

@@ -59,3 +59,72 @@ func TestMapUtil_IFKeys(t *testing.T) {
 		t.Errorf("unexpected c: expected=C, got=%s", c)
 	}
 }
+
+func TestMapUtil_KeyArg(t *testing.T) {
+	m := map[string]interface{}{}
+
+	key := []string{"a", "b", "c"}
+
+	Set(m, key, "C")
+
+	c := (((m["a"].(map[string]interface{}))["b"]).(map[string]interface{}))["c"]
+
+	if c != "C" {
+		t.Errorf("unexpected c: expected=C, got=%s", c)
+	}
+}
+
+func TestMapUtil_IndexedKeyArg(t *testing.T) {
+	m := map[string]interface{}{}
+
+	key := []string{"a", "b[0]", "c"}
+
+	Set(m, key, "C")
+
+	c := (((m["a"].(map[string]interface{}))["b"].([]interface{}))[0].(map[string]interface{}))["c"]
+
+	if c != "C" {
+		t.Errorf("unexpected c: expected=C, got=%s", c)
+	}
+}
+
+type parseKeyTc struct {
+	key    string
+	result map[int]string
+}
+
+func TestMapUtil_ParseKey(t *testing.T) {
+	tcs := []parseKeyTc{
+		{
+			key: `a.b.c`,
+			result: map[int]string{
+				0: "a",
+				1: "b",
+				2: "c",
+			},
+		},
+		{
+			key: `a\.b.c`,
+			result: map[int]string{
+				0: "a.b",
+				1: "c",
+			},
+		},
+		{
+			key: `a\.b\.c`,
+			result: map[int]string{
+				0: "a.b.c",
+			},
+		},
+	}
+
+	for _, tc := range tcs {
+		parts := ParseKey(tc.key)
+
+		for index, value := range tc.result {
+			if parts[index] != value {
+				t.Errorf("unexpected key part[%d]: expected=%s, got=%s", index, value, parts[index])
+			}
+		}
+	}
+}