Cleanup includes in sources

Mainly just removes some unused includes, but sometimes the include
is replaced by a smaller header instead.

src/catch2/internal/catch_section.cpp

@@ -6,7 +6,7 @@
 
 // SPDX-License-Identifier: BSL-1.0
 #include <catch2/internal/catch_section.hpp>
-#include <catch2/internal/catch_run_context.hpp>
+#include <catch2/interfaces/catch_interfaces_capture.hpp>
 #include <catch2/internal/catch_uncaught_exceptions.hpp>
 #include <catch2/internal/catch_move_and_forward.hpp>