fix(webapp): `is` attr only works with `component`

* Add filter rule to prevent future ones
* Preparation for vue3 migration

Reference:
https://v3-migration.vuejs.org/breaking-changes/custom-elements-interop.html
https://eslint.vuejs.org/rules/no-deprecated-html-element-is.html

www/webapp/.eslintrc.js

@@ -21,6 +21,7 @@ module.exports = {
     'vue/no-multi-spaces': 'warn',
     'vue/no-deprecated-filter': 'warn', // Preparation for vue3
     'vue/no-deprecated-v-on-number-modifiers': 'warn', // Preparation for vue3
+    'vue/no-deprecated-html-element-is': 'warn', // Preparation for vue3
   },
   ignorePatterns: ['**/src/modules/**/*'],
   parserOptions: {

www/webapp/src/views/ConfirmationPage.vue

@@ -23,7 +23,7 @@
           <v-card-text>
             <error-alert :errors="errors"></error-alert>
             <v-form @submit.prevent="confirm" class="mb-4" v-model="valid" ref="form">
-              <div
+              <component
                       :is="this.actionHandler"
                       :payload="this.post_payload"
                       :response="this.post_response"
@@ -32,7 +32,7 @@
                       ref="actionHandler"
                       @autosubmit="confirm"
                       @clearerrors="clearErrors"
-              ></div>
+              ></component>
             </v-form>
             <h2 class="text-h6">Keep deSEC Going</h2>
             <p>