feat: create BaseButton component (#1123)

Co-authored-by: Dominik Pschenitschni <mail@celement.de>
Reviewed-on: https://kolaente.dev/vikunja/frontend/pulls/1123
Reviewed-by: konrad <k@knt.li>
Co-authored-by: Dominik Pschenitschni <dpschen@noreply.kolaente.de>
Co-committed-by: Dominik Pschenitschni <dpschen@noreply.kolaente.de>

src/components/tasks/partials/relatedTasks.vue

@@ -6,7 +6,7 @@
 			class="is-pulled-right add-task-relation-button"
 			:class="{'is-active': showNewRelationForm}"
 			v-tooltip="$t('task.relation.add')"
-			type="secondary"
+			variant="secondary"
 			icon="plus"
 			:shadow="false"
 		/>