Move SwiftTool creation out of individual commands

The SwiftTool initializer performs some global configuration steps,
so it isn't really safe to require that individual commands create
an instance, even when they don't need one. This moves the
customization point to a run(_ swiftTool: SwiftTool) method.

Author: natecook1000

Sources/Commands/SwiftBuildTool.swift

@@ -55,9 +55,6 @@ struct BuildToolOptions: ParsableArguments {
         return allSubsets.first ?? .allExcludingTests
     }
 
-    @OptionGroup()
-    var swiftOptions: SwiftToolOptions
-    
     /// If the test should be built.
     @Flag(help: "Build both source and test targets")
     var buildTests: Bool
@@ -76,20 +73,21 @@ struct BuildToolOptions: ParsableArguments {
 }
 
 /// swift-build tool namespace
-public struct SwiftBuildTool: ParsableCommand {
+public struct SwiftBuildTool: SwiftCommand {
     public static let configuration = CommandConfiguration(
         commandName: "swift build",
         abstract: "Build sources into binary products",
         discussion: "SEE ALSO: swift run, swift package, swift test",
         version: Versioning.currentVersion.completeDisplayString,
         helpNames: [.short, .long, .customLong("help", withSingleDash: true)])
 
+    @OptionGroup()
+    var swiftOptions: SwiftToolOptions
+
     @OptionGroup()
     var options: BuildToolOptions
 
-    public func run() throws {
-        let swiftTool = try SwiftTool(options: options.swiftOptions)
-
+    public func run(_ swiftTool: SwiftTool) throws {
         if options.shouldPrintBinPath {
             try print(swiftTool.buildParameters().buildPath.description)
             return