[Embed block] Implement Bottom Sheet to set a link

[ceyhun]

Description

• Implement Bottom Sheet to set a link for Embed block
• When a block placeholder is added, bottom sheet is automatically opened
• Link field is auto-focused (labeled “Embed link”)
• If there is a link in the clipboard it is auto-pasted
• Can type a link if empty
• Can close before typing and re-open by pressing on the embed block placeholder
• Can open by pressing the pen icon in the toolbar when an existing embed block is selected
• Can click on the “Learn more about embeds” link at the bottom to open the support article in the browser: https://wordpress.org/support/article/embeds/
• Close the bottom sheet after typing a link. If the link is not a valid URL, a warning message is shown

Screenshot

Existing	Placeholder