Add keymap wrappers for introspection into the keymap. (#17229)

* Introspection handlers for keymaps.

* Renaming.

quantum/keymap_introspection.h

@@ -0,0 +1,15 @@
+// Copyright 2022 Nick Brassel (@tzarc)
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#include <stdint.h>
+
+// Get the number of layers defined in the keymap
+uint8_t keymap_layer_count(void);
+
+#if defined(ENCODER_ENABLE) && defined(ENCODER_MAP_ENABLE)
+
+// Get the number of layers defined in the encoder map
+uint8_t encodermap_layer_count(void);
+
+#endif // defined(ENCODER_ENABLE) && defined(ENCODER_MAP_ENABLE)