Add optional vcpkg bootstrapping for dependencies

[DaveyJonesBitPail]

Description

• Define vcpkg manifest and add optional bootstrapping.
• Bootstrap option is on by default
• Align vcpkg with baseline expected in manifest
• Cache vcpkg and package installs across OS and vcpkg.json hash
• Consume pugixml w/ header-only def if bootstrapped
• Bump version

Additional notes

• We now have another version defined in the vcpkg.json. This should align with the version defined in CMakeLists.txt. There ought to be a graceful way to have a single source of truth.
• The dependencies resolved via vcpkg are not pinned to specific versions. Thankfully this worked so far, however we should consider using a vcpkg lock file or being explicit with overrides in the manifest
• The build scripts could use a cleanup/restructuring. Adding the lots of if conditions does not make for easily readable and robust build scripts....

Fixes # (issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Describe the tests that you ran to verify your changes.
Provide instructions to reproduce.

Checklist:

• I followed the Contributing Guidelines.
• I did a self-review.
• I commented my code, particularly in hard-to-understand areas.
• I updated the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.

[ptahmose]

This is damn cool - thanks!

[m-aXimilian]

The only thing I am not directly convinced is that inc_libCZI.h is now inc_libCZI.h.in. Other than that it looks good to me despite the missing documentation update in version-history.md.
Btw: I think we should increment to 0.6.5 judging from the version-history file. (I failed to increment the version in the root CMakeLists.txt in the last commit...sorry!)

[DaveyJonesBitPail]

The only thing I am not directly convinced is that inc_libCZI.h is now inc_libCZI.h.in. Other than that it looks good to me despite the missing documentation update in version-history.md. Btw: I think we should increment to 0.6.5 judging from the version-history file. (I failed to increment the version in the root CMakeLists.txt in the last commit...sorry!)

Hmmm, that's a fair point. It would make things a good bit cleaner. Thanks!

[m-aXimilian]

LGTM