Generic components

[gskorokhod]

Now that we have the new data model with proper classes, we can significantly reduce code duplication for selector / badge components by writing them in a generic way.

As far as UI is concerned, we have the following kinds of objects:

• Those with a name and an icon (Task, Skill, Shift)
• Those with a name and an avatar (Person, Location)
• Fallback: those that only have a name (Assignment?)

These can be represented as interfaces, and the components can be written like so:

<script lang="ts" generics="T extends HasAvatar">
    object: T | undefined = undefined;
    ...
</script>

[gskorokhod]

Done in #38