Rename some matcher-related files

The two changes are
`catch_matchers_templates` -> `catch_matchers_templated` and
`catch_matchers_generic` -> `catch_matchers_predicate`. The former
is mostly cosmetic, but the second was previously significantly
misleading, and as the library is now to be consumed by including
specific headers, this needed to be fixed.

tests/ExtraTests/X01-PrefixedMacros.cpp

@@ -5,7 +5,7 @@
 // This won't provide full coverage, but it might be worth checking
 // the other branch as well
 #include <catch2/catch_test_macros.hpp>
-#include <catch2/matchers/catch_matchers_generic.hpp>
+#include <catch2/matchers/catch_matchers_predicate.hpp>
 #include <catch2/matchers/catch_matchers_string.hpp>
 
 #include <type_traits>