fix(vcproject): use dynamic binding to avoid assembly load failure

[CalvinAllen]

Summary

• Removes compile-time reference to Microsoft.VisualStudio.VCProjectEngine and replaces it with dynamic late binding
• The previous fix (fix(vsix): include VCProjectEngine assembly in VSIX package #33) bundled the assembly in the VSIX, but users still reported the same FileNotFoundException on both VS 2022 and VS 2026
• By using dynamic, the VCProjectEngine assembly is only resolved at runtime when actually handling a C++ project, preventing the error for all other project types

Root Cause

The JIT compiler needed to resolve VCProject and VCConfiguration types when compiling OpenProjectBinFolder, even for non-C++ projects. This caused an assembly load failure for users without the C++ workload installed, regardless of whether the assembly was bundled in the VSIX.

Test plan

• Open a C#/VB.NET/F# project in VS 2022 and use "Open Bin Folder" — should work without errors
• Open a C++ project in VS 2022 (with C++ workload) and use "Open Bin Folder" — should work correctly
• Verify on VS 2026

Resolves #32