Case insensitive filter in group topics view

[kszapsza]

• Filter in GroupTopicsListing view is case insensitive, so that we can find e.g. MyFavoriteTopic by typing myfavoritetopic. Same for GroupListing (though generally group names are lowercase either way).
• Fix Unresolved function or method toBeInTheDocument() warnings in hermes-console-vue tests (add jest to globals in tsconfigs).

[szczygiel-m]

Can You also apply this change to other listings? E.g subscription search in topicView

[kszapsza]

When we have content: string | undefined, we can have undefined value, but the key content has to be present in the object, so in stubs we have to write: content: undefined (otherwise we have a type error).

In case of content?: string, we can both have object with key content with value undefined provided explicitly, but we also can omit this key completely (e.g. in test data, the value of absent key will still be undefined in JS).

[kszapsza]

Previous approach in which we mapped either to object (name/color/statusText/href) or to null and then filtered with .filter(Boolean) was problematic for TS type system. Though the operation filtered out null objects, IntelliJ still complained in Vue template below, that subscriptionItems elements can be possibly null.

We could introduce an interface:

interface SubscriptionListItem {
  name: string;
  color: string;
  statusText: State;
  href: string;
} 

and then change .filter(Boolean) filter to the so-called TypeScript type predicate:

.filter((subscription): subscription is SubscriptionListItem => subscription !== null)

then TS type system would know, that null values possibly introduced in map above were filtered out.

But IMHO it is cleaner to simply perform subscription filtering before map, as I did here