feat(behaviors): Add macro support.

* Fine grainted press/release/tap actions.
* TIming between actions can be controlled.
* Processed async, to avoid blocking.

app/tests/macros/basic/native_posix.keymap

@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) 2022 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+ 
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan_mock.h>
+#include "../behavior_keymap.dtsi"
+
+&kscan {
+	events = <ZMK_MOCK_PRESS(0,0,10) ZMK_MOCK_RELEASE(0,0,1000)>;
+};