fix(mapper): ensure web-forms.html is loaded from url root, not relative to project

Author: spwoodcock

src/mapper/src/lib/components/forms/wrapper.svelte

@@ -254,7 +254,7 @@
 										style:height="100%"
 										use:handleIframe
 										title="odk-web-forms-wrapper"
-										src={`./web-forms.html?projectId=${projectId}&entityId=${entityId}&formXml=${formXml}&odkWebFormUrl=${odkWebFormUrl}&formMedia=${encodeURIComponent(JSON.stringify(formMedia))}&cssFile=${commonStore.config?.cssFileWebformsOverride || ''}`}
+										src={`/web-forms.html?projectId=${projectId}&entityId=${entityId}&formXml=${formXml}&odkWebFormUrl=${odkWebFormUrl}&formMedia=${encodeURIComponent(JSON.stringify(formMedia))}&cssFile=${commonStore.config?.cssFileWebformsOverride || ''}`}
 									></iframe>
 								{/if}
 							{/key}