Introduce a list of image mime types we can support as images

E.g. TIFF will now be handled as a generic file, not image, even though it has mime prefix "image/"

src/components/create/CreateRoomAvatar.vue

@@ -4,7 +4,7 @@
         <v-icon class="create-room-avatar__icon default" v-else>$vuetify.icons.room_avatar_placeholder</v-icon>
         <v-icon class="create-room-avatar__camera clickable" v-if="!modelValue || !modelValue.image" @click.stop="showRoomAvatarPicker">$vuetify.icons.ic_camera</v-icon>
         <input id="room-avatar-picker" ref="roomAvatar" type="file" name="roomAvatar"
-            @change="handlePickedRoomAvatar($event)" accept="image/*" class="d-none" />
+            @change="handlePickedRoomAvatar($event)" :accept="supportedImageTypes" class="d-none" />
     </div>
 </template>