Move filesystem into Config

The filesystem object was available through ModuleContext.Fs(), but
gives too much access to the filesystem without enforicing correct
dependencies.  In order to support sandboxing the soong_build
process move the filesystem into the Config.  The next change will
make it private.

Bug: 146437378
Test: all Soong tests
Change-Id: I5d3ae9108f120fd335b21efd612aefa078378813

android/visibility_test.go

@@ -868,7 +868,7 @@ func TestVisibility(t *testing.T) {
 func testVisibility(buildDir string, fs map[string][]byte) (*TestContext, []error) {
 
 	// Create a new config per test as visibility information is stored in the config.
-	config := TestArchConfig(buildDir, nil)
+	config := TestArchConfig(buildDir, nil, "", fs)
 
 	ctx := NewTestArchContext()
 	ctx.RegisterModuleType("package", PackageFactory)
@@ -879,9 +879,7 @@ func testVisibility(buildDir string, fs map[string][]byte) (*TestContext, []erro
 	ctx.PreArchMutators(RegisterDefaultsPreArchMutators)
 	ctx.PreArchMutators(RegisterVisibilityRuleGatherer)
 	ctx.PostDepsMutators(RegisterVisibilityRuleEnforcer)
-	ctx.Register()
-
-	ctx.MockFileSystem(fs)
+	ctx.Register(config)
 
 	_, errs := ctx.ParseBlueprintsFiles(".")
 	if len(errs) > 0 {