outpkg not respected when inpackage: True is set

[LandonTClipp]

This happens in generator.go:

// GeneratePrologue generates the prologue of the mock.
func (g *Generator) GeneratePrologue(ctx context.Context, pkg string) {
	g.populateImports(ctx)
	if g.config.InPackage {
		g.printf("package %s\n\n", g.iface.Pkg.Name())
	} else {
		g.printf("package %v\n\n", pkg)
	}

	g.generateImports(ctx)
	g.printf("\n")
}

The outpkg parameter is completely ignored in this case, which prevents us from giving the mocks a package name like original_pkg_test. I will create a parameter that allows us to override this behavior and always respect outpkg. Sadly, we have to retain backwards compatability.