fatfs: Make fatfs runnable on host

Makes fatfs component runnable on host. Depends on the host library build
of wear levelling and flash emulator. Includes a basic sanity test of
mounting a volume, opening a file, writing to the file, reading the file,
closing the file and unmounting volume.

components/fatfs/test_fatfs_host/main.cpp

@@ -0,0 +1,2 @@
+#define CATCH_CONFIG_MAIN
+#include "catch.hpp"