Add letter icon option for collections

app/scenes/CollectionEdit.tsx

@@ -100,7 +100,12 @@ const CollectionEdit = ({ collectionId, onSubmit }: Props) => {
             autoFocus
             flex
           />
-          <IconPicker onChange={handleChange} color={color} icon={icon} />
+          <IconPicker
+            onChange={handleChange}
+            color={color}
+            initial={name[0]}
+            icon={icon}
+          />
         </Flex>
         <InputSelect
           label={t("Sort in sidebar")}

app/scenes/CollectionNew.tsx

@@ -141,6 +141,7 @@ class CollectionNew extends React.Component<Props> {
           <IconPicker
             onOpen={this.handleIconPickerOpen}
             onChange={this.handleChange}
+            initial={this.name[0]}
             color={this.color}
             icon={this.icon}
           />