Start migrating clipboard_button helper to ::Pajamas::ButtonComponent

What does this MR do and why?

Start migrating clipboard_button helper to ::Pajamas::ButtonComponent.

Since the clipboard_button helper is being used in many places at the moment, it might be safer to migrate usages iteratively. This MR proposes a first iteration that...

• ...renames clipboard_button to deprecated_clipboard_button.
• ...introduces a new clipboard_button helper that renders a ::Pajamas::ButtonComponent under the hood.
• ...migrates a couple usages to the newer helper.

Re #417829 (closed), #417844 (closed)

Screenshots or screen recordings

	Before	After
app/views/projects/commits/_commit.html.haml
app/views/shared/_mobile_clone_panel.html.haml

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MR acceptance checklist

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