커스텀 테마 UX 개선 (#286)

* 키보드 기본 완료버튼 넣기

* 색상 추가 간격 수정

* 빼먹은 애니메이션 수정

* 고정테마 정렬 & 자동스크롤

* Apply SwiftFormat changes

* Change theme pin on/off icon

* Fix typo

* Cleanup code

* Apply SwiftFormat changes

---------

Co-authored-by: shp7724 <shp7724@users.noreply.github.com>
Co-authored-by: peng-u-0807 <penguin0807@snu.ac.kr>

Author: shp7724

SNUTT-2022/SNUTT/Assets/Assets.xcassets/Icons/theme.pin.off.imageset/Contents.json

@@ -1,7 +1,7 @@
 {
   "images" : [
     {
-      "filename" : "pin_off.png",
+      "filename" : "theme.pin.off.png",
       "idiom" : "universal",
       "scale" : "1x"
     },
@@ -12,12 +12,12 @@
           "value" : "dark"
         }
       ],
-      "filename" : "push_pin_off.png",
+      "filename" : "theme.pin.off.dark.png",
       "idiom" : "universal",
       "scale" : "1x"
     },
     {
-      "filename" : "pin_off@2x.png",
+      "filename" : "theme.pin.off@2x.png",
       "idiom" : "universal",
       "scale" : "2x"
     },
@@ -28,12 +28,12 @@
           "value" : "dark"
         }
       ],
-      "filename" : "push_pin_off@2x.png",
+      "filename" : "theme.pin.off.dark@2x.png",
       "idiom" : "universal",
       "scale" : "2x"
     },
     {
-      "filename" : "pin_off@3x.png",
+      "filename" : "theme.pin.off@3x.png",
       "idiom" : "universal",
       "scale" : "3x"
     },
@@ -44,7 +44,7 @@
           "value" : "dark"
         }
       ],
-      "filename" : "push_pin_off@3x.png",
+      "filename" : "theme.pin.off.dark@3x.png",
       "idiom" : "universal",
       "scale" : "3x"
     }