event handler options integration

[maxence-charriere]

This PR adds support for event handlers options in order define scope or passive options. @oderwat can you take a look on this and tell whether it would solve your issue?

Usage:

// Event with scope
app.Div().OnScroll(func(cox app.Context, e app.Event){}, app.EventScope("1"))

// Passive event
app.Div().OnScroll(func(cox app.Context, e app.Event){}, app.PassiveEvent())

// Multiple options
app.Div().OnScroll(func(cox app.Context, e app.Event){},
    app.PassiveEvent(),
    app.EventScope("1"),
)