add SearchView helper component

app/src/components/SearchView.vue

@@ -0,0 +1,46 @@
+<template>
+  <div>
+    <view-top-bar>
+      <template #group-left>
+        <b-input-group id="search-group" class="w-100">
+          <b-input-group-prepend is-text>
+            <icon iname="search" />
+          </b-input-group-prepend>
+
+          <b-form-input
+            id="top-bar-search"
+            :value="search" @input="$emit('update:search', $event)"
+            :placeholder="$t('search.for', { items: $tc('items.' + itemsName, 2) })"
+            :disabled="!items"
+          />
+        </b-input-group>
+      </template>
+
+      <slot name="top-bar-buttons" slot="group-right" />
+    </view-top-bar>
+
+    <b-alert v-if="items === null || filteredItems === null" variant="warning" show>
+      <slot name="alert-message">
+        <icon iname="exclamation-triangle" />
+        {{ $t(items === null ? 'items_verbose_count' : 'search.not_found', { items: $tc('items.' + itemsName, 0) }) }}
+      </slot>
+    </b-alert>
+
+    <slot v-else name="default" />
+
+    <slot name="extra"/>
+  </div>
+</template>
+
+<script>
+export default {
+  name: 'SearchView',
+
+  props: {
+    search: { type: String, required: true },
+    itemsName: { type: String, required: true },
+    items: { type: null, required: true },
+    filteredItems: { type: null, required: true }
+  }
+}
+</script>