[6.0] Add In-process plugin server path

[rintaro]

Cherry-pick #1616 into release/6.0

(copied from swiftlang/swift#74740)

• Explanation: swift-syntax libraries in compiler has been complied with -enable-library-evolution because the toolchain provides them as a public interface for building plugins (i.e. lib/swift/host/*.swiftmodule). But that was not great for the performance in the compiler. This PR changes that by separating swift-syntax libs for the compiler from the one for the plugins. So the compiler and the plugin now can use different version/ABI of swift-syntax libraries from the compiler. Now swift-syntax for the compiler are compiled without library evolution.
• Scope: Macro plugins
• Risk: Mid. This changes the mechanism of in-process plugins significantly. Now in-process plugins are communicate with the compiler using the same messaging serialization with other plugins (i.e. swift-plugin-server, and other executable plugins), instead of directly calling the Macro.Type expansion method. Also, to separate the swift-syntax libraries, this introduces another set of shared swift-syntax libraries in the toolchain.
• Testing: Passes current test suite.
• Issue: rdar://130532628
• Reviewer: Hamish Knight (@hamishknight) Alex Hoppen (@ahoppen) Ben Barham (@bnbarham)

[rintaro]

swiftlang/swift#74740
swiftlang/swift-syntax#2702
swiftlang/llvm-project#8929
swiftlang/swift-installer-scripts#309
@swift-ci Please test

[rintaro]

Decided not to merge