make 'for' argument optional in TooltipLabel

The latest svelte-check has revealed we were not passing 'for' in
when we should have been. This is a quick hack to get the tests passing
again, but a better approach that actually makes this accessible again
would be good in the future.

ts/deck-options/CheckBoxRow.svelte

@@ -5,7 +5,6 @@
 <script lang="ts">
     import Row from "./Row.svelte";
     import Col from "./Col.svelte";
-    import Label from "./Label.svelte";
     import TooltipLabel from "./TooltipLabel.svelte";
     import CheckBox from "./CheckBox.svelte";
     import RevertButton from "./RevertButton.svelte";
@@ -20,7 +19,7 @@
         <RevertButton bind:value {defaultValue} />
         <CheckBox bind:value
             >{#if markdownTooltip}<TooltipLabel {markdownTooltip}><slot /></TooltipLabel
-                >{:else}<Label><slot /></Label>{/if}</CheckBox
+                >{:else}<slot />{/if}</CheckBox
         >
     </Col>
 </Row>

ts/deck-options/TooltipLabel.svelte

@@ -10,12 +10,16 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     import Badge from "components/Badge.svelte";
 
     export let markdownTooltip: string;
-    let forId: string;
+    let forId: string | undefined = undefined;
     export { forId as for };
 </script>
 
 <span>
+    {#if forId}
         <Label for={forId}><slot /></Label>
+    {:else}
+        <slot />
+    {/if}
     <WithTooltip
         tooltip={marked(markdownTooltip)}
         showDelay={250}