mbedTLS: Update to new LTS v3.6.0

Keep module compatibility with mbedtls 2.x (old LTS branch).

A patch has been added to allow compiling after removing all the `psa_*`
files from the library folder (will look into upstreaming it).

Note: mbedTLS 3.6 finally enabled TLSv1.3 by default, but it requires
some module changes, and to enable PSA crypto (new "standard" API
specification), so it might be best done in a separate commit/PR.

core/crypto/crypto_core.cpp

@@ -39,6 +39,9 @@
 #include <mbedtls/md5.h>
 #include <mbedtls/sha1.h>
 #include <mbedtls/sha256.h>
+#if MBEDTLS_VERSION_MAJOR >= 3
+#include <mbedtls/compat-2.x.h>
+#endif
 
 // RandomGenerator
 CryptoCore::RandomGenerator::RandomGenerator() {