make ui.open accept NiceGUI element as link target

[retsyo]

doc on Navigate on large pages says we can simply pass a NiceGUI element as link target:

label_B = ui.label('sth')
ui.link('Goto B', label_B)

which is a handy method. However, sometimes I don't need a ui.link but, for example, a ui.button. So I write

def fnB():
    ui.open(label_B)

ui.button('Goto B', on_click=fnB)

however, I get

KeyError: <nicegui.elements.label.Label object at 0x000001D79AF728C0>

So for consistency in concept with ui.link, I suggest to make ui.open accept NiceGUI element as link target too.

p.s. for now, we can still use

ui.link_target('target_A')
ui.label('sth')

def fnA():
    ui.open('#target_A')

ui.button('Goto A', on_click=fnA)

or

with ui.button(''):
        ui.link('Goto B', label_B)

[falkoschindler]

Thanks for the suggestion, @retsyo! It's pretty convincing.
The implementation should be straight forward, given the code in ui.link. Would you like to create a pull request? 🙂