Support for PC platform (#12)

* improvements for cross-platform compiling

* moved tactility-core to libs/

* splitup improvements

* remove git/gitmodules from freertos

* better platformbetter platform checks

* added build scripts

* delete mbedtls

* re-add mbedtls

* fixes and improvements

* added pc build

* simplify build scripts

* revert build scrpit

* updated builds

* fix for pc

* fix for pc

* fix for build

libs/mbedtls/configs/ext/config_tfm.h

@@ -0,0 +1,13 @@
+/*
+ *  Empty placeholder
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+/*
+ * This file is intentionally empty.
+ *
+ * Having an empty file here allows us to build the TF-M config, which references this file,
+ * without making any changes to the TF-M config.
+ */