Add `show_label` property to `gr.Sidebar`

[ExcellentAmericanEagle]

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Is your feature request related to a problem? Please describe.
Currently, the label passed to gr.Sidebar isn't visible by design. As documented:

label: name of the sidebar. Not displayed to the user.

This is a weird built in behavior because normally in other gradio components the label is always rendered to the user in some way.

Describe the solution you'd like
I suggest adding show_label property to gr.Sidebar that's set to False by default (to preserve current behavior). Setting this to True will render the label next to the arrow in the sidebar toggle button only when the sidebar is closed

with gr.Sidebar(label="Errors (2)", open=True, width=300, show_label=True):

Collapsed:

Expanded:

Additional context
Currently there can only be a single gr.Sidebar instance that takes effect in the system.
Adding labels to the toggle button is one step ahead for supporting multiple gr.Sidebars.

[ExcellentAmericanEagle]

I'm working on a PR, unfortunately, the CSS when assigning position="left" is kinda wonky for this purpose:

[abidlabs]

Cool, I think this is reasonable, although we should make sure that adding the label doesn't cause the collapsed icon to grow too wide so that it "touches" components in the main page. cc @dawoodkhan82