IO-2175 Category Dropdown Clear

Allow for clear and correct for Select allowClear sending undefined and convert that to null. Overload UndefinedtoNull to have an array of keys

client/src/components/jobs-detail-general/jobs-detail-general.component.jsx

@@ -256,7 +256,7 @@ export function JobsDetailGeneral({ bodyshop, jobRO, job, form }) {
       </FormRow>
       <FormRow header={t("jobs.forms.other")}>
         <Form.Item label={t("jobs.fields.category")} name="category">
-          <Select disabled={jobRO}>
+          <Select disabled={jobRO} allowClear>
             {bodyshop.md_categories.map((s) => (
               <Select.Option key={s} value={s}>
                 {s}