Add system setting to mirror bluetooth pairing database to sd card (#1787)

* ams_mitm: add ability to mirror bluetooth device pairing database to sd card via a system setting

* ams_mitm: address requested stylistic changes

* ams_mitm: make use of R_SUCCEED macro

* ams_mitm: use settings::BluetoothDevicesSettings instead of libnx type

* ams_mitm: fix logic error when truncating pairing database on read

* Update .ini comment

* ams_mitm: missing R_TRY around call to fs::FlushFile

* stratosphere: remove union from BluetoothDevicesSettings type

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Co-authored-by: ndeadly <24677491+ndeadly@users.noreply.github.com>

stratosphere/ams_mitm/source/set_mitm/settings_sd_kvs.cpp

@@ -393,6 +393,11 @@ namespace ams::settings::fwdbg {
             /* 0 = Disabled, 1 = Enabled */
             R_ABORT_UNLESS(ParseSettingsItemValue("atmosphere", "enable_log_manager", "u8!0x0"));
 
+            /* Controls whether the bluetooth pairing database is redirected to the SD card (shared across sysmmc/all emummcs) */
+            /* NOTE: On <13.0.0, the database size was 10 instead of 20; booting pre-13.0.0 will truncate the database. */
+            /* 0 = Disabled, 1 = Enabled */
+            R_ABORT_UNLESS(ParseSettingsItemValue("atmosphere", "enable_external_bluetooth_db", "u8!0x0"));
+
             /* Hbloader custom settings. */
 
             /* Controls the size of the homebrew heap when running as applet. */