goose: add a test for imports across packages

Reviewed-by: Tuo Shan <shantuo@google.com>
Reviewed-by: Herbie Ong <herbie@google.com>

internal/goose/testdata/PkgImport/foo/foo.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+
+	"bar"
+)
+
+func main() {
+	fmt.Println(injectFooBar())
+}
+
+type Foo int
+type FooBar int
+
+//goose:provide Set
+func provideFoo() Foo {
+	return 41
+}
+
+//goose:import Set "bar".Bar
+
+//goose:provide Set
+func provideFooBar(foo Foo, barVal bar.Bar) FooBar {
+	return FooBar(foo) + FooBar(barVal)
+}