externalXmlSettings.xmlFileAssociations not used in getXMLSettings

[JuneStepp]

It looks like getXMLSettings doesn't use external XML file associations, causing that part of the Typescript API to be broken.

Currently, the code is:

//applying externalXmlSettings to the xmlSettings
  externalXmlSettings.xmlCatalogs.forEach(catalog => {
    if (!xml['xml']['catalogs'].includes(catalog)) {
      xml['xml']['catalogs'].push(catalog);
    }
  })

when it probably should be something like:

  //applying externalXmlSettings to the xmlSettings
  externalXmlSettings.xmlCatalogs.forEach(catalog => {
    if (!xml['xml']['catalogs'].includes(catalog)) {
      xml['xml']['catalogs'].push(catalog);
    }
  })
  externalXmlSettings.xmlFileAssociations.forEach(element => {
    if (!xml['xml']['fileAssociations'].some(fileAssociation => fileAssociation.systemId === element.systemId)) {
      xml['xml']['fileAssociations'].push(element);
    }
  });

This was the only way I was able to get the addXMLFileAssociations function of the API to work, but please tell me if I'm just missing something. I have practically no experience with typescript or vscode extensions.

[JuneStepp]

Looks like the right code was there in the original pull request but got lost here: https://github.com/redhat-developer/vscode-xml//commit/72cce613494b149fec2d79fe5de81409c5c6db3f when another feature was added.