Flyout: convert current flyout to web component

[humitos]

As the first step, we want to copy the current flyout code and and convert it into a web component. It should work in the exact same way as the one generated by the current JS code and HTML returned by the endpoint.

It has to be floating at the bottom right for the first iteration.

This will allow us to start slowly migrating new projects to use the new flyout, and expose the other addons.

Front conversations

[humitos]

There is an initial implementation for this at #66. However, it changes the design and we don't want that for this initial iteration.

[humitos]

Take into account these PRs when working on this issue (cc @zanderle):

• Flyout: Use raw SVG instead of FontAwesome webfont readthedocs.org#9297
• Make flyout menu scrollable readthedocs.org#7375

[zanderle]

Do we want to replicate the styles exactly? This is what we have so far:

It's basically the same (the layout and the functionality) apart from the colors (which can be changed using css variables).