Overhaul for 5.9

[ndiego]

Added

• Add additional border support (color, width, style)
• Add margin support
• Add the ability to set an aria-label on the icon and link.
• Add the core Unlock icon.
• Add the core Comment Author Avatar icon.
• Add the core Comment Author Name icon.
• Add the core Comment Content icon.
• Add the core Comment Edit Link icon.
• Add the core Comment Reply Link icon.

Changed

• Update inserter modal components to use isFullScreen to better resemble core modals.
• Update styling on inserter modals for improved mobile responsiveness.
• Import the Align None, Color, Reset, and Styles icons directly from @wordpress/icons.
• Remove the custom search component in favor of the core component from @wordpress/components.
• Restructure stylesheets to better conform with block standards.

Fixed

• Fix bug where hyphens and colons would be incorrectly stripped from attribute names in custom icons. Thanks @stokesman for the PR. (#5)