Add CSS and JS syntax highlighting

[mhils]

This PR adds "css" and "javascript" syntax highlighting.

[Copilot]

Pull Request Overview

This PR adds syntax highlighting support for CSS and JavaScript in addition to the existing XML and YAML highlighting functionality.

• Updated function signatures and language enums to incorporate "css" and "javascript".
• Added new modules and tests for CSS and JavaScript syntax highlighting.
• Adjusted dependency ordering in Cargo.toml and updated changelog accordingly.

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
mitmproxy-rs/mitmproxy_rs/syntax_highlight.pyi	Extended language literal to include CSS and JavaScript.
mitmproxy-highlight/src/yaml.rs	Renamed functions to a consistent naming scheme and updated tests.
mitmproxy-highlight/src/xml.rs	Renamed functions to a consistent naming scheme and updated tests.
mitmproxy-highlight/src/lib.rs	Expanded Language enum and updated match logic to include new variants.
mitmproxy-highlight/src/javascript.rs	Added new module for JavaScript syntax highlighting with tests.
mitmproxy-highlight/src/css.rs	Added new module for CSS syntax highlighting with tests.
mitmproxy-highlight/src/common.rs	Renamed internal test function to reflect tag usage.
mitmproxy-highlight/Cargo.toml	Added new dependencies and reordered existing ones.
CHANGELOG.md	Documented changes for CSS and JS syntax highlighting.