Install GSL.natvis

[jpr42]

Turns out supporting GSL.natvis perfectly is quite difficult.

There is no universal way to consume .natvis files that would satisfy everyone.

I thought the solution was to use the /NATVIS linker option. But it turns out that actually embeds information into the PDB. So I'm not sure how to properly support the Ninja generator...

That's not even accounting for the fact target_link_options doesn't play nicely with /NATVIS when installing.

When you just add the file via target_sources the visual studio solution will just pick it up and recognize it without adding it to the PDB file. Which won't affect the binary and is what most devs want.

This all comes down to the fact that /NATVIS files have native integration with visual studio that makes it difficult to use with non-visual studio solutions. /NATVIS almost works but embeds itself into the PDB which not everyone wants, and not everyone generates PDBs either.

Docs for natvis files and /NATVIS

• https://learn.microsoft.com/en-us/visualstudio/debugger/create-custom-views-of-native-objects?view=vs-2022
• https://learn.microsoft.com/en-us/cpp/build/reference/natvis-add-natvis-to-pdb?view=msvc-170

So my current solution is to just simplify the existing CMake code, and install the natvis so the user can decide.

closes #1084

[dmitrykobets-msft]

@jpr42 Thanks a lot for looking into this! Unfortunate that natvis support is so limited, but the cleanup you've done to work around it looks good.