Update MicroBuildSwixPlugin 1->4 (#7468)
Update MicroBuildSwixPlugin 1->4 (#7468)

This fixes an issue with manifests containing duplicate entries.
rainersigwald/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild,rainersigwald/msbuild,sean-gilliam/msbuild,rainersigwald/msbuild,rainersigwald/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild,AndyGerlicher/msbuild