Support multiple ResultTags annotations

[jmmills]

As multiple  As annotations are supported, it would make sense to support multiple ResultTag annotations.

Currently this code fails with cannot apply more than one line of ResultTags

func main() {
    app := fx.New(
        fx.Provide(
            fx.Annotate(
                func() *bytes.Buffer {
                    return bytes.NewBuffer([]byte("Hello!"))
                },
                fx.ResultTags(`name:"a"`),
                fx.ResultTags(`name:"b"`),
            ),
        ),
        fx.Invoke(
            fx.Annotate(
                func(a, b *bytes.Buffer) {
                    fmt.Println(a.String())
                    fmt.Println(b.String())
                },
                fx.ParamTags(
                    `name:"a"`,
                    `name:"b"`,
                ),
            ),
        ),
    )
    app.Run()
}

A work-around is possible by providing multiple copies of the same instance of a type, however it is less intuitive.

fx.Provide(
    fx.Annotate(
        func() (*bytes.Buffer, *bytes.Buffer) {
            a := bytes.NewBuffer([]byte("Hello!"))
            b := a
            return a, b
        },
        fx.ResultTags(`name:"a"`, `name:"b"`),
    ),
)

Is this a breaking change? It should not be a breaking change as nothing (sans tests) should rely on app failure for multiple result tag annotations.