Improve vcpkg port file generation and handling

[abeltrano]

Type

• Bug fix
• Feature addition
• Feature update
• Documentation
• Build Infrastructure

Side Effects

• Breaking change
• Non-functional change

Goals

• Eliminate requirement to manually calculate SHA512 hash of git ref archive used by vcpkg port file.
• Clarify usage of vcpkg in project.
• Fix logic to detect latest version from tags (previously only considered annotated tags).

Technical Details

• Fix logic to determine project version from tags by listing all tags instead of just annotated ones. The prior logic only considered annotated tags and not lightweight tags, and unfortunately GitHub release tags are not annotated ones.
• Remove all ${VCPKG_TARGET_*} variables and logic, since the generated port file isn't used locally anymore and is consolidated to only generate the official/release version of the port file.
• Use vcpkg_from_github instead of vcpkg_from_git such that the generate port file can be used directly, as-is in vcpkg registries or overlays.
• Move toolchain-specific CMake configuration into separate cmake script file under cmake directory.

Test Results

• Built on both Linux and Windows and verified versioning was correct.
• TBD: Incorporate generated port file into Windows build and validate it.
• TBD: Rebuild dev container and validate it works.

Reviewer Focus

• None

Future Work

• None

Checklist

• Build target all compiles cleanly.
• clang-format and clang-tidy deltas produced no new output.
• Newly added functions include doxygen-style comment block.