Manually exclude Java2Swift.config files from targets that don't use the plugin

This eliminates warnings about the Java2Swift.config files being "unhandled".
SwiftPM is correct to warn here, because the files aren't used from SwiftPM
themselves (we're not using the build plugin to generate them).

Author: DougGregor

Package.swift

@@ -160,6 +160,7 @@ let package = Package(
     .target(
       name: "JavaKit",
       dependencies: ["JavaRuntime", "JavaKitMacros", "JavaTypes"],
+      exclude: ["Java2Swift.config"],
       swiftSettings: [
         .swiftLanguageMode(.v5),
         .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])
@@ -168,6 +169,7 @@ let package = Package(
     .target(
       name: "JavaKitJar",
       dependencies: ["JavaKit"],
+      exclude: ["Java2Swift.config"],
       swiftSettings: [
         .swiftLanguageMode(.v5),
         .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])
@@ -176,6 +178,7 @@ let package = Package(
     .target(
       name: "JavaKitNetwork",
       dependencies: ["JavaKit"],
+      exclude: ["Java2Swift.config"],
       swiftSettings: [
         .swiftLanguageMode(.v5),
         .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])
@@ -184,6 +187,7 @@ let package = Package(
     .target(
       name: "JavaKitReflection",
       dependencies: ["JavaKit"],
+      exclude: ["Java2Swift.config"],
       swiftSettings: [
         .swiftLanguageMode(.v5),
         .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])