Feat/autocomplete with metadatawidget

[jusa3]

1. AutocompleteWidget: The hover information of the option doesn't have any design. Add the MetadataWidget for additional and styled information. Doesn't include entity source or source URL yet (should we add this information to the MetadataWidget?). Unstyled hover information still present - should be removed after adding the source information to the MetadataWidget - do not merge this PR before.

Caveat: Not accessible - no links can be clicked and only one tab can be displayed.

Solves #127

2. MetadataWidget: Data not available will result in a blank. Use conditionals to avoid spaces.

Before:

After:

Solves #176

[Pooya-Oladazimi]

@jusa3

Nice idea! I just noticed two points:

1- The hover menu should be removed now that we have this in my opinion:

2- There is a loading symbol that appears in a small box next to the autocomplete when one hovers over the result. It happens very fast which makes it hard to take a screenshot.

[jusa3]

I can remove the old hover menu when we decide what we do with the source and source URL so that no feature gets lost.

It's the loading spinner of the MetadataWidget. The default position of the tooltip is "top" so it first appears on top with the loading spinner and when the data loads and the data is too large for the top position it gets displayed at the bottom. I'm afraid we can't change this behaviour.

[jusa3]

First answer this question: #183
and have a look into accessibility.