CodeLens for registering/unregistering catalog

[angelozerr]

It should be nice to insert in catalog xml file a Codelens [Register catalog] to insert it to the list of catalog (see xml.catalogs).

[Register catalog]
<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog">
  <uri name="http://docs.oasis-open.org/odata/ns/edmx" uri="./schemas/edmx.xsd" />
  <uri name="http://docs.oasis-open.org/odata/ns/edm" uri="./schemas/edm.xsd" />
</catalog>

When catalog.xml is already registered, it should be nice to have a [Unregister catalog] codelens.

It should be good to have a vscode command and quickfix for that too.

[angelozerr]

I would like to work on this issue because in my case when I test some user issues, I need to check if user catalog.xml is registered or not by reading the settings.json.

With those codelens it will b ereally easy to know if XML catalog is registered in the settings.json and it will be really easy to register / unregister XML catalogs.