Investigate size impact of SwiftSyntax dependency

[compnerd]

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Windows switched a while ago to statically linking the full SourceKit-LSP binary because it netted a size win (reduction). The recent dependency on SwiftSyntax may change the calculus, particularly with the driver also depending on SwiftSyntax. I wonder what the total cost is for the static vs dynamic linking.

[compnerd]

CC: @DougGregor @etcwilde

[ahoppen]

rdar://103602514