feat: display edit history diff (#922)

* build: add google's diff-match-patch

Copied from 62f2e689f4/java/src/name/fraser/neil/plaintext/diff_match_patch.java

* feat(status/edit-history): display diff for text

Closes https://github.com/sk22/megalodon/issues/789

* fix(status/edit-history): add fake poll id

* code style adjustments

* don't diff if only formatting changed

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Co-authored-by: sk <sk22@mailbox.org>

mastodon/src/main/java/org/joinmastodon/android/model/Status.java

@@ -264,7 +264,7 @@ public class Status extends BaseModel implements DisplayItemsParent, Searchable{
 		s.visibility=StatusPrivacy.PUBLIC;
 		s.reactions=List.of();
 		s.mentions=List.of();
-		s.tags =List.of();
+		s.tags=List.of();
 		s.emojis=List.of();
 		s.filtered=List.of();
 		return s;