Pass Config to NewTestContext instead of ctx.Register

Prepare for using Config when adding singletons by passing
Config to NewTestContext and NewContext instead of to ctx.Register.
This will enable a followup change to store SingletonMakeVarsProviders
registered on the Context in the Config, which is necessary to run
multiple tests in parallel without data races.

Test: all soong tests
Change-Id: Id229629a4e42ff4487d317241673837726c075fc
diff --git a/android/arch_test.go b/android/arch_test.go
index 8525b03..4cef4c8 100644
--- a/android/arch_test.go
+++ b/android/arch_test.go
@@ -353,9 +353,9 @@
 		t.Run(tt.name, func(t *testing.T) {
 			config := TestArchConfig(buildDir, nil, bp, nil)
 
-			ctx := NewTestArchContext()
+			ctx := NewTestArchContext(config)
 			ctx.RegisterModuleType("module", archTestModuleFactory)
-			ctx.Register(config)
+			ctx.Register()
 			if tt.config != nil {
 				tt.config(config)
 			}
@@ -442,9 +442,9 @@
 		t.Run(tt.name, func(t *testing.T) {
 			config := TestArchConfigNativeBridge(buildDir, nil, bp, nil)
 
-			ctx := NewTestArchContext()
+			ctx := NewTestArchContext(config)
 			ctx.RegisterModuleType("module", archTestModuleFactory)
-			ctx.Register(config)
+			ctx.Register()
 			if tt.config != nil {
 				tt.config(config)
 			}