Use tags from status when adding handlers to hashtag spans in status content (#2344)

* Migrate LinkHelper to kotlin

* Support tags field on statuses

* Use embedded tags list in status instead of text scraping to embed tag click handler.
Fixes #2283

* Make mentions and tags lists nonnullable

* Make LinkHelper.openLink a Context extension method

* Use builtin extension for uri conversion

* More cleanup in LinkHelper

* Add tests for LinkHelper.getDomain

* Unbreak tags in places that don't have a tag list (e.g. profiles)

* Fixup javadoc

app/src/test/java/com/keylesspalace/tusky/components/timeline/StatusMocker.kt

@@ -40,6 +40,7 @@ fun mockStatus(id: String = "100") = Status(
     visibility = Status.Visibility.PUBLIC,
     attachments = ArrayList(),
     mentions = emptyList(),
+    tags = emptyList(),
     application = Status.Application("Tusky", "https://tusky.app"),
     pinned = false,
     muted = false,