Resolve an issue building test products.

After #7353 landed, I noticed that the build products for test targets were not
being emitted correctly. swift-testing and XCTest produce separate build
products (with distinct names) but this wasn't happening as intended. It turns
out that the changes to split `buildParameters` into `productsBuildParameters`
and `toolsBuildParameters` weren't fully propagated to our testing
infrastructure.

I also noticed `SWIFT_PM_SUPPORTS_SWIFT_TESTING` wasn't being set correctly
anymore (same root cause) although we've decided to ignore that flag over in
swift-testing anyway (see swiftlang/swift-testing#376.)

This regression caused build failures in swift-testing (e.g. [here](https://ci.swift.org/job/pr-swift-testing-macos/663/console))
with the telltale failure signature:

> /Users/ec2-user/jenkins/workspace/pr-swift-testing-macos/branch-main/swift-testing/.build/x86_64-apple-macosx/debug/swift-testingPackageTests.xctest/Contents/MacOS/swift-testingPackageTests: /Users/ec2-user/jenkins/workspace/pr-swift-testing-macos/branch-main/swift-testing/.build/x86_64-apple-macosx/debug/swift-testingPackageTests.xctest/Contents/MacOS/swift-testingPackageTests: cannot execute binary file

Which indicates that it thinks the filename for the swift-testing build product
is the XCTest bundle's executable.

This PR plumbs through the two build parameters arguments to everywhere in
`swift test` and `swift build` that needs them and resolves the issue.

Author: grynspan

Sources/Commands/SwiftBuildCommand.swift

@@ -149,8 +149,7 @@ package struct SwiftBuildCommand: AsyncSwiftCommand {
             throw ExitCode.failure
         }
         if case .allIncludingTests = subset {
-            var buildParameters = try swiftCommandState.productsBuildParameters
-            for library in try options.testLibraryOptions.enabledTestingLibraries(swiftCommandState: swiftCommandState) {
+            func updateTestingParameters(of buildParameters: inout BuildParameters, library: BuildParameters.Testing.Library) {
                 buildParameters.testingParameters = .init(
                     configuration: buildParameters.configuration,
                     targetTriple: buildParameters.triple,
@@ -161,18 +160,25 @@ package struct SwiftBuildCommand: AsyncSwiftCommand {
                     testEntryPointPath: globalOptions.build.testEntryPointPath,
                     library: library
                 )
-                try build(swiftCommandState, subset: subset, buildParameters: buildParameters)
+            }
+            var productsBuildParameters = try swiftCommandState.productsBuildParameters
+            var toolsBuildParameters = try swiftCommandState.toolsBuildParameters
+            for library in try options.testLibraryOptions.enabledTestingLibraries(swiftCommandState: swiftCommandState) {
+                updateTestingParameters(of: &productsBuildParameters, library: library)
+                updateTestingParameters(of: &toolsBuildParameters, library: library)
+                try build(swiftCommandState, subset: subset, productsBuildParameters: productsBuildParameters, toolsBuildParameters: toolsBuildParameters)
             }
         } else {
-            try build(swiftCommandState, subset: subset)
+            try build(swiftCommandState, subset: subset, productsBuildParameters: nil, toolsBuildParameters: nil)
         }
     }
 
-    private func build(_ swiftCommandState: SwiftCommandState, subset: BuildSubset, buildParameters: BuildParameters? = nil) throws {
+    private func build(_ swiftCommandState: SwiftCommandState, subset: BuildSubset, productsBuildParameters: BuildParameters?, toolsBuildParameters: BuildParameters?) throws {
         let buildSystem = try swiftCommandState.createBuildSystem(
             explicitProduct: options.product,
             shouldLinkStaticSwiftStdlib: options.shouldLinkStaticSwiftStdlib,
-            productsBuildParameters: buildParameters,
+            productsBuildParameters: productsBuildParameters,
+            toolsBuildParameters: toolsBuildParameters,
             // command result output goes on stdout
             // ie "swift build" should output to stdout
             outputStream: TSCBasic.stdoutStream