MSVC: Restore support for non-incremental linking with v100 toolset and older

Since commit 0b552eb877 (MSVC: Embed manifests directly for
non-incremental vs_link_exe links, 2023-02-20, v3.27.0-rc1~438^2) we use
`/MANIFEST:EMBED`, but that is not supported by older MSVC linkers.
Restore use of the standalone manifest tool.

Update `Tests/MSManifest` to recognize `dpiAwareness` in the manifest
content as written by MSVC v100 tooling.

Fixes: #26179