Add Support for RustOwl in Helix Editor

[BernardIgiri]

RustOwl ([GitHub](https://github.com/cordx56/rustowl)) is a tool designed to visualize ownership and lifetimes in Rust, providing developers with a clearer understanding of how variables are managed. It currently supports Neovim and VS Code, but many of us would love to see it working with Helix.

There is already an open issue on RustOwl's side ([Issue #15](cordx56/rustowl#15)) requesting Helix support. So I am writing this request on the Helix repo to see what can be done on the Helix side.

The resulting enhancement should allow RustOwl to integrate with Helix, providing real-time ownership and lifetime visualization. Ideally, RustOwl's visualization should be rendered in a way that fits well with Helix's existing syntax highlighting and inline hints.

[nik-rev]

Looks like RustOwl is a language server but it also would require a plugin system to integrate since it seems to need some extra features and it is specifically for Rust (and Helix tries not to include language-specific stuff no matter how awesome it is. For example surrounding selection with HTML tags, while easy to implement - is not supported).

You would need plugins to be able to highlight regions of code with custom colors for example