Migrating some of ddio functions to use std::filesystem::path

[winterheart]

Pull Request Type

• [ ] GitHub Workflow changes
• [ ] Documentation or Wiki changes
• [x] Build and Dependency changes
• [ ] Runtime changes
  • [ ] Render changes
  • [ ] Audio changes
  • [ ] Input changes
  • [ ] Network changes
  • [ ] Other changes

Description

This is initial PR for migrating some of FS operations to C++17 std::filesystem. Converting some of global variables to std::filesystem::path, greatly refactored LockFile functions (now using with C++ IOOps / IOStreams), unify some platform-dependent function to cross-platform variants.

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Checklist

• [x] I have tested my changes locally and verified that they work as intended.
• [x] I have documented any new or modified functionality.
• [x] I have reviewed the changes to ensure they do not introduce any unnecessary complexity or duplicate code.
• [x] I understand that by submitting this pull request, I am agreeing to license my contributions under the project's license.

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