browser: RIP modules, long live gosh+v23test

Also, per discussion:
- Moves 'v23test' package to x/ref/test/v23test
- Makes 'expect' package explicitly depend on 'testing', now
that 'modules' doesn't pass it an interface

MultiPart: 4/7

Change-Id: I8830984c6ce48104b804ba9613069a3f5ee9cb06
diff --git a/go/src/v.io/x/browser/runner/main.go b/go/src/v.io/x/browser/runner/main.go
index bdac39b..a8c8eaa 100644
--- a/go/src/v.io/x/browser/runner/main.go
+++ b/go/src/v.io/x/browser/runner/main.go
@@ -26,12 +26,12 @@
 	"v.io/x/lib/set"
 	"v.io/x/ref"
 	"v.io/x/ref/lib/signals"
-	"v.io/x/ref/lib/v23test"
 	_ "v.io/x/ref/runtime/factories/generic"
 	"v.io/x/ref/services/identity/identitylib"
 	"v.io/x/ref/services/mounttable/mounttablelib"
 	"v.io/x/ref/services/xproxy/xproxy"
 	"v.io/x/ref/test/expect"
+	"v.io/x/ref/test/v23test"
 )
 
 // NOTE(sadovsky): It appears that a lot of this code has been copied from