Home Link block: add more shapes & allow inserting anywhere

[annezazu]

We should add some shapes to home link block (circle, dot, square, triangle) and allow inserting anywhere (outside nav menu). It's a highly convenient way of linking to the home if you don't want to use the site title name. Here's a video demonstrating current limitations (lack of shapes and inability to insert elsewhere):

home.link.mov

Pulled from: #48443

[richtabor]

A shape block in general may be fun.

[carolinan]

I found that to insert the block anywhere there needs to be a way to detect, in PHP, if the block is inside the navigation block or not. There is no built in way to do this currently.
This is because the default wrapping element is an <li> which should not be used when the block is placed elsewhere.

[ntsekouras]

Navigation block seems to provides/adds lot of context. Maybe we could use this info to determine if it's inside a Navigation block? 🤔 .

From some super quick testing(removing the "parent": [ "core/navigation" ], the Home Link's block context was empty when outside the Navigation block and full when inside. If we could make sure that when inside Navigation a specific context property is always added, we could update the returned html. --cc @getdave

[getdave]

We should have block context coming from Navigation if it's a child of Navigation. So it should be possible. We probably do something similar for Page List.