qmlls: lints out-of-date versions of files in the linter

Reproducer steps:

1. Have a Main.qml file with this content:

   import QtQuick
   
   Item {
       enum Qwer { ASDF, INCORRECT, ZXCV }
   
       property var myEnum: Main.CORRECT
   }
   

2. save the file
3. modify {{enum Qwer { ASDF, INCORRECT, ZXCV }

   }} to {{enum Qwer

   { ASDF, CORRECT, ZXCV }

   }}

4. See that the qmlls linter still complains about the unknown enum value
5. Save the file
6. Now the qmlls linter knows about the enum value