Add build prebuilts support for any version of swift-syntax. (#8994)

Removes the hardcoding of the contents of the prebuilt libraries.

Adds a --version argument to specify which versions of swift-syntax you
want to build for. You can have multiple of these. We add a sample
build.sh script to the folder to show an example, including finding the
most recent prerelease of 602.

Also removes the hardcoding of the list of products that go into the
library. Instead we ask the package for its list of library products and
add them all.

Finally, removes the header files since SwiftPM now hooks up the include
paths to the CModules from the source in the checkouts.

Author: dschaefer2

Package.swift

@@ -786,6 +786,9 @@ let package = Package(
                 .product(name: "ArgumentParser", package: "swift-argument-parser"),
                 "Basics",
                 "Workspace",
+            ],
+            exclude: [
+                "build.sh"
             ]
         ),