Fix multiple accessibility defects identified by AXE (#10606)

* Mark effects overlay canvas as aria hidden

* Ensure date separators aren't seen as focusable aria separators

* Fix

* Fix font slider not having aria label

* Add missing aria labels

* Fix settings flags setting aria-checked={null}

* Update snapshots

src/components/views/settings/FontScalingPanel.tsx

@@ -128,6 +128,7 @@ export default class FontScalingPanel extends React.Component<IProps, IState> {
                         onChange={this.onFontSizeChanged}
                         displayFunc={(_) => ""}
                         disabled={this.state.useCustomFontSize}
+                        label={_t("Font size")}
                     />
                     <div className="mx_FontScalingPanel_fontSlider_largeText">Aa</div>
                 </div>

src/components/views/settings/devices/SelectableDeviceTile.tsx

@@ -35,10 +35,11 @@ const SelectableDeviceTile: React.FC<Props> = ({ children, device, isSelected, o
                 className="mx_SelectableDeviceTile_checkbox"
                 id={`device-tile-checkbox-${device.device_id}`}
                 data-testid={`device-tile-checkbox-${device.device_id}`}
-            />
-            <DeviceTile device={device} onClick={onClick} isSelected={isSelected}>
-                {children}
-            </DeviceTile>
+            >
+                <DeviceTile device={device} onClick={onClick} isSelected={isSelected}>
+                    {children}
+                </DeviceTile>
+            </StyledCheckbox>
         </div>
     );
 };

src/components/views/settings/tabs/room/NotificationSettingsTab.tsx

@@ -284,6 +284,7 @@ export default class NotificationsSettingsTab extends React.Component<IProps, IS
                                     onClick={chromeFileInputFix}
                                     onChange={this.onSoundUploadChanged}
                                     accept="audio/*"
+                                    aria-label={_t("Upload custom sound")}
                                 />
                             </form>