Tests: remove @testable import Workspace

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

Author: compnerd

Tests/WorkspaceTests/RegistryPackageContainerTests.swift

@@ -18,7 +18,7 @@ import PackageLoading
 import PackageModel
 import PackageRegistry
 import _InternalTestSupport
-@testable import Workspace
+import Workspace
 import XCTest
 
 import struct TSCUtility.Version

Tests/WorkspaceTests/SourceControlPackageContainerTests.swift

@@ -18,7 +18,7 @@ import PackageLoading
 import PackageModel
 import SourceControl
 import _InternalTestSupport
-@testable import Workspace
+import Workspace
 import XCTest
 
 import enum TSCUtility.Git

Tests/WorkspaceTests/ToolsVersionSpecificationRewriterTests.swift

@@ -16,7 +16,7 @@
 
 import Basics
 import PackageModel
-@testable import Workspace
+import Workspace
 import Testing
 
 /// Test cases for `rewriteToolsVersionSpecification(toDefaultManifestIn:specifying:fileSystem:)`

Tests/WorkspaceTests/WorkspaceStateTests.swift

@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 import Basics
-@testable import Workspace
+import Workspace
 import Testing
 
 fileprivate struct WorkspaceStateTests {

Tests/WorkspaceTests/WorkspaceTests.swift

@@ -20,7 +20,7 @@ import PackageRegistry
 import PackageSigning
 import SourceControl
 import SPMBuildCore
-@testable import Workspace
+import Workspace
 import XCTest
 
 import struct TSCBasic.ByteString