Update transform_view to exemplar-based INTERFACE configuration

[ednolan]

No description provided.

[coveralls]

coverage: 100.0%. remained the same
when pulling e63d5d2 on enolan_exemplarify2
into e5d92f5 on main.

[JeffGarland]

The statement below is valid -- we really need to separate the readme for building versus 'using in your project'.

[JeffGarland]

Let me clarify what I'm talking about:

This library is header only.  If you want to use `beman.transform_view` from your
project, you can include `beman/transform_view/*.hpp` files from your C++ source
files

For me this is a valid way to use the library -- especially if you're using a non-cmake build system. It's a very common way to use header only libraries because it's easy and portable. We shouldn't discourage it just because some of our core members don't want to consume libraries this way.

The more general issue is that the examplar 'readme outline' is a mess. In my view all this 'building for developmentsort of text shouldn't be mixed in with the 'how do I just use this in my project: aka conan, vcpkg, etc. I think @ednolan has mentioned that thebuilding for development` should probably be a linked .md file so that the primary markdown can be radically simplified and less overwhelming.

So we don't need to fix it here now -- but it's bugging me :)

[tzlaine]

This all seems fine to me. Are Jeff's comments blocking this? I'm unclear if I should merge it as-is.

[JeffGarland]

I merged the one thing that really needed changing -- the unconditional requirement of ctest even when not building tests.