[Minor] Refactor MSBuild project structure

[Belonit]

Refactors the MSBuild project layout and prepares the build configuration for safer optimized builds.

Changes:

• Split Phobos build settings into Phobos.props.
• Import project-wide props from Phobos.vcxproj.
• Cleaned up duplicated and redundant MSBuild settings.
• Prepared linker retention settings for WPO/LTCG compatibility.

Note:

The macro changes are a workaround needed to prevent the linker from removing records from custom sections such as .patch, .syexe00, and .syhks00.

Without these anchors, the linker may treat those symbols as unused and discard them when WPO/LTCG is enabled.

[github-actions]

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