Use SrcDir and absolute paths for improved build reliability and portability.

[stevewgr]

Description

This pull request includes two key changes aimed at improving project maintainability and robustness:

1. Use SrcDir Instead of SolutionDir:

   • Replaces the usage of the SolutionDir variable with the SrcDir variable.
   • The SolutionDir variable can be problematic when building a specific project directly, especially when passing a .vcxproj file to msbuild instead of a .sln file. In such cases, SolutionDir is undefined and can break the build.
   • Using SrcDir makes the project more portable and resilient to directory relocations.

2. Replace Relative Paths with Absolute Paths Using SrcDir:

   • Converts all relative paths to absolute paths by leveraging the SrcDir variable.
   • This change enhances project maintenance and ensures better handling of directory relocations.

Benefits

• Improved Build Reliability: By avoiding the undefined SolutionDir variable, builds are more consistent and less prone to failures when using different project files.
• Enhanced Portability: Absolute paths with SrcDir make the project structure more robust and adaptable to changes in directory locations.
• Simplified Maintenance: The use of absolute paths and a consistent directory reference streamlines project upkeep and reduces path-related issues.

[stevewgr]

Build passing: https://github.com/ko4life-net/ko/actions/runs/10278200148/job/28441471408

Merging.