feat(bluetooth): Add back profiles, split fixes.

* Add back in profiles, not using Zephyr
  BT identity infrastructure.
* Restore additional `&bt` commands for profile
  operations.
* Fix for split pairing and subscriptions, since
  Zephyr persists subscriptions across connects.
* Remove keymap from peripheral builds, reduces
  firmware size, and avoids unneeded attempts
  to send HID data.

app/include/zmk/ble/profile.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2020 Peter Johanson <peter@peterjohanson.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <bluetooth/addr.h>
+
+#define ZMK_BLE_PROFILE_NAME_MAX 15
+
+struct zmk_ble_profile {
+    char name[ZMK_BLE_PROFILE_NAME_MAX];
+    bt_addr_le_t peer;
+};