Add simple runtime benchmarks

For now we add just two binaries, one with assertions taking the
fast path, one with assertions taking the slow path, and the ability
to run 1 of `REQUIRE(true)`, `REQUIRE_NOTHROW`, `REQUIRE_THROWS`
in a loop.

I also split off a CMake preset which enables more tests than the
basic `simple-tests` preset, but does not enable the most expensive
tests which force recompilation of Catch2 multiple times.

benchmarks/runtime_assertion_benches.cpp

@@ -0,0 +1,27 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+#include <catch2/catch_test_macros.hpp>
+
+TEST_CASE("Simple REQUIRE - 10M") {
+    for (size_t i = 0; i < 10'000'000; ++i) {
+        REQUIRE(true);
+    }
+}
+
+TEST_CASE("Simple NOTHROW - 10M") {
+    for (size_t i = 0; i < 10'000'000; ++i) {
+        REQUIRE_NOTHROW([](){}());
+    }
+}
+
+TEST_CASE("Simple THROWS - 10M") {
+    for (size_t i = 0; i < 10'000'000; ++i) {
+        REQUIRE_THROWS([]() { throw 1; }());
+    }
+}