* update eslint's `comma-dangle` rule to `always-multiline`
* add check and fix scripts to package.json
* Invoke `yarn fix` to adopt the updated eslint rules. No other changes are included.
* RN-519: Expands AtMentions and ChannelMentions searches to use entire device height.
* RN-519: Fix for ~ and @ search list heights.
* RN-519: Optimization.