Add default value for longform field

packages/standard-components/src/forms/LongFormField.svelte

@@ -6,6 +6,7 @@
   export let label
   export let placeholder
   export let disabled = false
+  export let defaultValue = ""
 
   let fieldState
   let fieldApi
@@ -15,10 +16,10 @@
   {label}
   {field}
   {disabled}
+  {defaultValue}
   type="longform"
   bind:fieldState
   bind:fieldApi
-  defaultValue=""
 >
   {#if fieldState}
     <CoreTextArea