namelist support: highlighting; folding; outline

[MuellerSeb]

Closes: #1296

This pull request adds comprehensive support for Fortran Namelist files (.nml, .namelist) to the extension. It introduces syntax highlighting, folding, outline (symbol) support, and proper language registration for these files. The changes include a new language configuration, a TextMate grammar, symbol provider logic, and updates to the extension's activation and manifest files.

Fortran Namelist Language Support

• Added a new language definition for Fortran Namelist in package.json, including file extensions, configuration, and icon. (package.jsonR120-R135)
• Registered the new language for activation and associated it with a TextMate grammar for syntax highlighting. ([1], [2])
• Introduced a language configuration file (language-configuration.namelist.json) to provide comment styles, bracket/quote pairs, and folding markers for Namelist files. (language-configuration.namelist.jsonR1-R30)
• Added a TextMate grammar (syntaxes/fortran_namelist.tmLanguage.json) for Namelist syntax highlighting, including keywords, assignments, numbers, strings, booleans, and comments. (syntaxes/fortran_namelist.tmLanguage.jsonR1-R58)

Namelist Outline/Symbol Support

• Implemented a NamelistDocumentSymbolProvider to provide outline support for Namelist files, enabling navigation of blocks and variables in the editor. Registered this provider in the extension activation logic. ([1], [2], [3])

Documentation

• Updated the README.md to advertise Namelist syntax highlighting, folding, and outline support. (README.mdR35)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.65%. Comparing base (1c8b212) to head (986c618).

Additional details and impacted files

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##             main    #1302   +/-   ##
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  Coverage   81.65%   81.65%           
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  Files          13       13           
  Lines        2436     2436           
  Branches      203      203           
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  Hits         1989     1989           
  Misses        442      442           
  Partials        5        5           

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[MuellerSeb]

@gnikit ping. 🙃

[gnikit]

I don't think this should be its own language id, see my comment

[gnikit]

I'm not sure if namelist should be its own language id. From a language perspective it is a Fortran feature. For how this extension is wired it should be defined in FreeForm injected like the other scopes, and then inherited via FixedForm without any need to modify.

The fact that it has dedicated extensions make it a bit annoying, but the above approach is reasonable and would work. As a side note an LSP would not consider them different entities so symbols will be parsed as normal sources and symbols will be displayed respectively, hence no need for the explicit fallback.