Added clear completed todos (#9782)

website/client/components/tasks/clearCompletedTodos.vue

@@ -0,0 +1,33 @@
+<template lang="pug">
+.text-center.delete-completed
+  .help-text {{ $t('clearCompletedDescription') }}
+  .btn.btn-danger(@click='clearTodos()') {{ $t('clearCompleted') }}
+</template>
+
+<style lang="scss">
+.delete-completed {
+  padding: 1em;
+
+  .help-text {
+    color: #878190;
+    font-size: 12px;
+  }
+
+  .btn-danger {
+    font-size: 12px;
+    padding: .4em .6em;
+    margin-top: .5em;
+  }
+}
+</style>
+
+<script>
+export default {
+  methods: {
+    clearTodos () {
+      if (!confirm(this.$t('clearCompletedConfirm'))) return;
+      this.$store.dispatch('tasks:clearCompletedTodos');
+    },
+  },
+};
+</script>