Rework bcat Crkbd and Lily58 modifier keys (#9692)

* Re-enable mouse keys to fix Chrome OS media keys

I'm not sure if there's a bug in Chrome OS, QMK, or both, but
EXTRAKEY_ENABLE isn't sufficient for media keys to work on Chrome OS.
Instead, MOUSEKEY_ENABLE is also required.

* Remove unnecessary SPLIT_USB_DETECT for Lily58

I've since swapped my Lily58 back to Elite-C v2 controllers with working
VBUS detection.

* Move Crkbd Esc and Ctrl keys; add some shortcuts

* Move MC_ALTT to userspace for cross-board support

* Sync Lily58 keymap with Crkbd

* Fix typos

users/bcat/bcat.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#include "quantum.h"
+
+enum user_keycodes {
+    MC_ALTT = SAFE_RANGE,
+    KEYMAP_SAFE_RANGE,
+};