Tests: remove @testable import Build

Use the newly extended APIs for testing and use a non-testable import of
the package, avoiding a recompilation.

Author: compnerd

Tests/BuildTests/BuildOperationTests.swift

@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-@testable import Build
+import Build
 @testable import PackageModel
 
 import Basics

Tests/BuildTests/BuildPlanTests.swift

@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import Basics
-@testable import Build
+import Build
 
 @testable
 @_spi(SwiftPMInternal)

Tests/BuildTests/BuildPlanTraversalTests.swift

@@ -14,7 +14,7 @@ import Foundation
 import Testing
 
 import Basics
-@testable import Build
+import Build
 
 import PackageGraph
 

Tests/BuildTests/ClangTargetBuildDescriptionTests.swift

@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import Basics
-@testable import Build
+import Build
 import PackageGraph
 import PackageModel
 import SPMBuildCore

Tests/BuildTests/CrossCompilationBuildPlanTests.swift

@@ -15,7 +15,7 @@ import class Basics.InMemoryFileSystem
 import class Basics.ObservabilitySystem
 import class Build.BuildPlan
 import class Build.ProductBuildDescription
-@testable import enum Build.ModuleBuildDescription
+import enum Build.ModuleBuildDescription
 import class Build.SwiftModuleBuildDescription
 import struct Basics.Triple
 import class PackageModel.Manifest

Tests/BuildTests/LLBuildManifestBuilderTests.swift

@@ -12,7 +12,7 @@
 import Foundation
 
 import Basics
-@testable import Build
+import Build
 import LLBuildManifest
 
 @_spi(DontAdoptOutsideOfSwiftPMExposedForBenchmarksAndTestsOnly)

Tests/BuildTests/ModuleAliasingBuildTests.swift

@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import Basics
-@testable import Build
+import Build
 
 @_spi(DontAdoptOutsideOfSwiftPMExposedForBenchmarksAndTestsOnly)
 import PackageGraph

Tests/BuildTests/PluginInvocationTests.swift

@@ -27,7 +27,7 @@ import _InternalTestSupport
 import Workspace
 import XCTest
 
-@testable import class Build.BuildPlan
+import class Build.BuildPlan
 import struct Build.PluginConfiguration
 
 import struct TSCUtility.SerializedDiagnostics

Tests/BuildTests/ProductBuildDescriptionTests.swift

@@ -10,7 +10,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-@testable
 import Build
 
 import class Basics.InMemoryFileSystem

Tests/BuildTests/WindowsBuildPlanTests.swift

@@ -14,7 +14,7 @@ import Foundation
 import Testing
 
 import Basics
-@testable import Build
+import Build
 import LLBuildManifest
 import _InternalTestSupport