Support Robot's libdoc xml format when defining 3rd party libraries

[Tattoo]

Generally with Robot Framework, one ends up with writing a lot of small libraries as well as employing the wealth of existing libraries in the ecosystem (see External tab)

Currently, Intellisense to be able to find keywords from 3rd party libraries by defining them keyword-by-keyword under rfLanguageServer.libraries setting.

Robot Framework has built-in documentation tool libdoc that 3rd party library developers are expected to use to document their libraries. This tool supports outputting library's keyword documentation in XML format, intended for editors and similar tools to have easily programmatically readable format. Users can also create these XML specs themselves as well from any library they might have.

It would be great, if I could simply define paths to the xmls I already have, something akin to this:

"rfLanguageServer.libraries": [
  {
    "name": "MyLibrary",
    "version": "1.0.0",
    "keywords": [
      { "name": "My Keyword 1", "args": ["arg1"], "doc": "documentation" },
      { "name": "My Keyword 2", "args": [],       "doc": "documentation" }
    ]
  },
 '/path/to/MyAnotherLibrary.xml',
'C:\\path\\to\\YetAnotherLibrary.xml'
]