Fix grpc vcpkg depdendency

[abeltrano]

Type

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

Side Effects

• Breaking change
• Non-functional change

Goals

• Ensure the project can be as part of a vcpkg port.

Technical Details

• The prior dependency for gRPC was marked as a host dependency, which is reserved for tools that are used in the build process. Unfortunately, the gRPC port isn't authored correctly to allow for the host-only port (this goes into it a bit). This prevented the CMake configuration file for gRPC to be found since vcpkg was looking for it in the wrong place. Update to use a standard target-based dependency, for which gRPC automatically (and correctly) takes a dependency internally on the host codegen feature.
• Add schema to root and Docker copies of vcpkg.json.
• Introduce a new CMake cache variable option NETREMOTE_VCPKG_BUILD_FOR_PORT that is to be set externally by the vcpkg port when the build is occurring in its behalf, allowing the build system to detect this scenario and take any vcpkg build-specific actions, including:
  • Omitting including the packaging directory.

Test Results

Confirmed the following builds:

• Local build with vcpkg artifact cache disabled.
• Docker build (TBD on GitHub post-merge).
• Windows build using razzle.

Reviewer Focus

• Consider whether this could break any configuration not tested or considered.

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.