tests: add proper catch2 handling

Add proper catch2 support:
 - add catch2 as a submodule
 - add cmake function to add test easily
 - discover each test in test binary
 - remove copies of catch.hpp
 - do not try to process tests for rt1051

Do not test internals of utf8, only public interface (nasty bugs could
occur otherwise).

Signed-off-by: Marcin Smoczyński <smoczynski.marcin@gmail.com>

module-db/tests/ThreadsTable_tests.cpp

@@ -10,19 +10,18 @@
 
 #include "vfs.hpp"
 
-#include "catch.hpp"
+#include <catch2/catch.hpp>
+
+#include "Database/Database.hpp"
+#include "Databases/SmsDB.hpp"
+#include "Tables/ThreadsTable.hpp"
 
-#include <stdint.h>
-#include <stdio.h>
-#include <string.h>
 #include <algorithm>
-
 #include <iostream>
 
-#include "../Database/Database.hpp"
-#include "../Databases/SmsDB.hpp"
-
-#include "Tables/ThreadsTable.hpp"
+#include <cstdint>
+#include <cstdio>
+#include <cstring>
 
 TEST_CASE("Threads Table tests")
 {
@@ -103,4 +102,4 @@ TEST_CASE("Threads Table tests")
     REQUIRE(smsdb.threads.GetCount() == 0);
 
     Database::Deinitialize();
-}
+}