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/CMakeLists.txt

@@ -0,0 +1,16 @@
+include(CatchMiscFunctions)
+
+add_executable(AssertionsFastPath
+  runtime_assertion_benches.cpp
+)
+
+add_executable(AssertionsSlowPath
+  runtime_assertion_benches.cpp
+  assertion_listener.cpp
+)
+
+target_link_libraries(AssertionsFastPath PRIVATE Catch2::Catch2WithMain)
+target_link_libraries(AssertionsSlowPath PRIVATE Catch2::Catch2WithMain)
+
+list(APPEND CATCH_TEST_TARGETS AssertionsFastPath AssertionsSlowPath)
+set(CATCH_TEST_TARGETS ${CATCH_TEST_TARGETS} PARENT_SCOPE)