Pygments Lexer for Fluent

The `fluent-pygments` library provides a Pygments lexer for Fluent (FTL), a powerful localization system designed for natural language. It enables syntax highlighting of Fluent files, particularly useful within documentation generators like Sphinx that leverage Pygments for code rendering. It is a component of the broader `python-fluent` project, which also includes `fluent.syntax` and `fluent.runtime`.