Switch to snake-casing for CSS classes

src/assets/stylesheets/create-object-dialog.scss

 @import 'shared';
 
-:local(.addMediaForm) {
+:local(.add-media-form) {
   display: flex;
   flex-direction: column;
   align-items: center;
@@ -8,7 +8,7 @@
   margin: 0;
 }
 
-:local(.actionButton) {
+:local(.action-button) {
   @extend %bottom-action-button;
   margin-left: 6px;
   margin-right: 6px;
@@ -25,27 +25,27 @@
   align-items: center;
 }
 
-:local(.smallButton) {
+:local(.small-button) {
   margin-left: 0.25em;
   font-size: 2em;
   align-self: center;
 }
 
-:local(.cancelIcon) {
+:local(.cancel-icon) {
   color: white;
   &:hover {
     color: #FF3D7F
   }
 }
 
-:local(.uploadIcon) {
+:local(.upload-icon) {
   color: white;
   &:hover {
     color: #2F80ED;
   }
 }
 
-:local(.inputBorder) {
+:local(.input-border) {
   display: flex;
   border: 0.25em solid white;
   border-radius: 1em;
@@ -56,7 +56,7 @@
   @extend %default-font;
 }
 
-:local(.leftSideOfInput) {
+:local(.left-side-of-input) {
   flex-grow: 1;
   border: none;
   white-space: nowrap;
@@ -68,7 +68,7 @@
   text-overflow: ellipsis; 
 }
 
-:local(.hideFileInput) {
+:local(.hide-file-input) {
   visibility: hidden;
   position: absolute;
 }