frontend: AutocompleteInput: escape * in fuzzyfinding

When inserting a suggestion, the value can have invalid characters, and
in particular `*` which can easily be present on the payee: field or
narration field.

Fixes beancount#1846

frontend/src/AutocompleteInput.svelte

@@ -72,6 +72,7 @@
       input != null && valueSelector != null
         ? valueSelector(suggestion, input)
         : suggestion;
+    value = value.replace("*", "\\*");
     dispatch("select", input);
     hidden = true;
   }