common/concepts: Rename IsBaseOf to DerivedFrom

This makes it more inline with its currently unavailable standardized
analogue std::derived_from.

While we're at it, we can also make the template match the requirements
of the standardized variant as well.

src/core/loader/loader.cpp

@@ -25,7 +25,7 @@ namespace Loader {
 
 namespace {
 
-template <Common::IsBaseOf<AppLoader> T>
+template <Common::DerivedFrom<AppLoader> T>
 std::optional<FileType> IdentifyFileLoader(FileSys::VirtualFile file) {
     const auto file_type = T::IdentifyType(file);
     if (file_type != FileType::Error) {