[proposal] expose tooltip directive

[tlouisse]

The platform has a tooltip built in with a great developer experience:

<button title="Agenda">📅</button>

A completely customizable lion-tooltip takes a bit more code:

<lion-tooltip>
  <button slot="invoker">📅</button>
  <div slot="content">Agenda<div>
</lion-tooltip>

Still ok, but imagine making a large menu/toolbar with many menu buttons in a row...

The DX would be improved if we could do:

<button ${title('Agenda')}>📅</button>

Or:

<button ${title(html`<b>Agenda</b>`)}>📅</button>

A working poc for this can be found here: https://github.com/ing-bank/lion/blob/poc/overlayEnhancementsTooltip/packages/overlays/docs/directives/tooltip.js

For maximum flexibility, it will support a local and global config object