Migration to styled-components

Here's a list based off @andrewda's list for adding unit tests to the app (https://github.com/gitpoint/git-point/issues/518), feel free to add/remove components if you think it's necessary.

**For newcomers:**
1. Choose the component you want to style
1. Comment here which component you'd like to work on
1. We'll update this list with your name
1. Make sure to include "before" and "after" screenshots in your submitted PR

# Loaders
- [x] LoadingListItem (@machour - #790)
- [x] LoadingMembersList (unclaimed)
- [x] LoadingRepositoryListItem (unclaimed)
- [x] LoadingRepositoryProfile (unclaimed)
- [x] LoadingUserListItem (@machour - #791)
- [x] LoadingModal (@machour - #792)

# Components
- [ ] IssueListItem (@josenaranjo - #578)
- [ ] RepositoryProfile (@shmesa22 - PR Pending)

# Screens

## issue
- [ ] EditIssue (unclaimed)
- [ ] IssueSettings (unclaimed)
- [x] NewIssue (unclaimed)
- [ ] PullMerge (unclaimed)

## repository
- [ ] IssueList (unclaimed)
- [ ] PullDiff (unclaimed)
- [ ] PullList (unclaimed)
- [ ] ReadMe (unclaimed)
- [ ] RepositoryCodeList (unclaimed)
- [ ] RepositoryFile (unclaimed)
- [x] Repository (@machour - #788)

Done:
- [x] Auth (@ZahraTee - #702)
- [x] Login (@machour - #787)
- [x] Notifications (@ZahraTee - #684)
- [x] Organization (@ZahraTee - #682)
- [x] Search (@Arjun-sna - #710)
- [x] User (@ZahraTee - #683)
- [x] Badge (@jpls93 – #535)
- [x] LoadingContainer (@machour - #782)
- [x] CodeLine (@josenaranjo – #561)
- [x] CommentInput (@shmesa22 – #596)
- [x] CommentListItem (@chinesedfan - #723)
- [x] DiffBlocks (@machour – #692)
- [x] EntityInfo (@MrLoh - #558)
- [x] ImageZoom (@MrLoh - #559)
- [x] InlineLabel (@binkpitch – #544)
- [x] IssueDescription (@josenaranjo - #563)
- [x] IssueEventListItem (@josenaranjo - #564)
- [x] LabelButton (@chinesedfan - #727)
- [x] LabelListItem (@pdong – #509)
- [x] Members (@shmesa22 - #606)
- [x] MentionArea (@binkpitch – #553)
- [x] NotificationIcon (@pdong – #510)
- [x] NotificationListItem (@LeoCp - #610)
- [x] ParallaxScroll (@shmesa22 - #607)
- [x] RepositoryListItem (@apoeco - #605)
- [x] RepositorySectionTitle (Useless component, see #730)
- [x] SectionList (@jamesg1 - #608)
- [x] StateBadge (@rkpasia - #715)
- [x] ViewContainer (@pdong – #508)
- [x] UserListItem (@shmesa22 - #601)
- [x] UserProfile (@chinesedfan – #724)
- [x] SearchBarAndroid (can't be migrated)

Start from the remaining unchecked components and screens listed in the issue, then review the completed migration entries for scope and conventions. Choose one unclaimed component, comment with your selection, and use the existing component implementation as the entry point. Done means the component is migrated and the pull request includes before-and-after screenshots.

索引モデルが issue の本文から書いたものです。