lib: improve lazy loading

The function call plus the existence check is more expensive than inlining the lazy require.

A few lazyAssert calls were obsolete as the assert would have to be required before.

I also moved a few lazy requires in the specific code path as it would not be required at all in some cases.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

lib