Add showing and modifying user name (#306)

Make sure to use the user name field everywhere

Add showing and modifying user name

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/frontend/pulls/306
Co-Authored-By: konrad <konrad@kola-entertainments.de>
Co-Committed-By: konrad <konrad@kola-entertainments.de>

src/components/tasks/edit-task.vue

@@ -107,7 +107,7 @@
 			<label class="label" for="">Assignees</label>
 			<ul class="assingees">
 				<li :key="a.id" v-for="(a, index) in taskEditTask.assignees">
-					{{ a.username }}
+					{{ a.getDisplayName() }}
 					<a @click="deleteAssigneeByIndex(index)">
 						<icon icon="times"/>
 					</a>

src/components/tasks/partials/comments.vue

@@ -17,7 +17,7 @@
 				<div class="media-content">
 					<div class="comment-info">
 						<img :src="c.author.getAvatarUrl(20)" alt="" class="image is-avatar" height="20" width="20"/>
-						<strong>{{ c.author.username }}</strong>&nbsp;
+						<strong>{{ c.author.getDisplayName() }}</strong>&nbsp;
 						<span v-tooltip="formatDate(c.created)">{{ formatDateSince(c.created) }}</span>
 						<span v-if="+new Date(c.created) !== +new Date(c.updated)" v-tooltip="formatDate(c.updated)">
 							· edited {{ formatDateSince(c.updated) }}