Add PreUp, PostUp, PreDown, PostDown for client (#1714)

* Fix create client popup background is not white

* Fix no Add button when client Allowed Ips or Server Allowed Ips is empty

* Add preUp preDown postUp postDown for client

* Add description of hooks for client config

* Move hooks's label text into 'hooks' in en.json

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Co-authored-by: yanghuanglin <yanghuanglin@qq.com>
Co-authored-by: Bernd Storath <999999bst@gmail.com>

src/app/pages/admin/hooks.vue

@@ -2,10 +2,26 @@
   <main v-if="data">
     <FormElement @submit.prevent="submit">
       <FormGroup>
-        <FormTextField id="PreUp" v-model="data.preUp" label="PreUp" />
-        <FormTextField id="PostUp" v-model="data.postUp" label="PostUp" />
-        <FormTextField id="PreDown" v-model="data.preDown" label="PreDown" />
-        <FormTextField id="PostDown" v-model="data.postDown" label="PostDown" />
+        <FormTextField
+          id="PreUp"
+          v-model="data.preUp"
+          :label="$t('hooks.preUp')"
+        />
+        <FormTextField
+          id="PostUp"
+          v-model="data.postUp"
+          :label="$t('hooks.postUp')"
+        />
+        <FormTextField
+          id="PreDown"
+          v-model="data.preDown"
+          :label="$t('hooks.preDown')"
+        />
+        <FormTextField
+          id="PostDown"
+          v-model="data.postDown"
+          :label="$t('hooks.postDown')"
+        />
       </FormGroup>
       <FormGroup>
         <FormHeading>{{ $t('form.actions') }}</FormHeading>