Multiple Vue apps support

To keep track of which tag has been added by which Vue app, VueMeta stores an unique in the data-vue-meta attribute.

Currently VueMeta only supports adding tags for multiple apps.

Adding , head or attributes is not supported. These will always be set to the values of the last app which triggered a metaInfo update.

On the client side the starts at and is incremented by one for each subsequent Vue app

For an SSR app which is served by a Node.js server, the appId would change for each request if we would increment it as on the client. Therefore we use the special ssrAppId so the is constant for every request.

On hydration VueMeta will check if the Vue app was server-rendered and if so set it's appId to as well.

It is possible to use cross app vmid's with two important caveats:

• _There is no fallback to use the vmid of a previous app_Given app1 and app2 both with a metaInfo property with vmid1, then when app2 removes its value for vmid1 there is no way to retrieve app1's value for vmid1 which means the element is removed