FEATURE: 372950
Task T9775
* Implement patch provided at: https://github.com/janusw/syntax-highlighting/commits/Fortran_2003_2008
* The `fortran-fixed.xml` file corresponds to the original file (`fortran.xml`), which is renamed. The `fortran-free.xml` file uses `IncludeRules` and include-keywords to avoid replicated code.
* Some unnecessary `RegExpr` rules are replaced for optimization.
TODO: ask for MIT license.