Put vue as dependency to sync with vue-template-compiler

[skjnldsv]

If apps/libs have their own vue dep, it makes updating this complicated as both deps needs to be updated simultaneously.
By having them all in @nextcloud/webpack-vue-config, we allos to upgrade them in the same flow

UPDATED: Manually downgraded the tests vue version, so that we can have a look and see if that works.
Theoretically, we should see the @nextcloud/webpack-vue-config's vue and vue-template-compiler version take over as deduped dependencies.

$ npm ls vue
webpack-vue-config-test@1.0.0 /home/admin/git/webpack-vue-config/tests
├─┬ @nextcloud/webpack-vue-config@5.4.0
│ └── vue@2.7.13 deduped
└── vue@2.7.13