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

java/dexpreopt_bootjars_test.go

@@ -44,14 +44,14 @@ func TestDexpreoptBootJars(t *testing.T) {
 		}
 	`
 
-	config := testConfig(nil)
+	config := testConfig(nil, bp, nil)
 
-	pathCtx := android.PathContextForTesting(config, nil)
+	pathCtx := android.PathContextForTesting(config)
 	dexpreoptConfig := dexpreopt.GlobalConfigForTests(pathCtx)
 	dexpreoptConfig.ArtApexJars = []string{"foo", "bar", "baz"}
 	setDexpreoptTestGlobalConfig(config, dexpreoptConfig)
 
-	ctx := testContext(bp, nil)
+	ctx := testContext()
 
 	ctx.RegisterSingletonType("dex_bootjars", dexpreoptBootJarsFactory)