feat(lsp): add yaml lsp

[hown3d]

add yaml-language server configuration in languages.toml

[pickfire]

Looks good to me. Thanks for adding this.

[the-mikedavis]

thanks!

[David-Else]

@hown3d Hi, thanks for adding this. I am having problems getting the formatting working, I have tried both the following but no luck:

[[language]]
name = "yaml"

# [language.config]
# yaml = { format.enable = true }

# config = { yaml.format.enable = true} 

It seems correct it is a boolean: https://github.com/search?q=yaml.format.enable&type=code

Have you any ideas? The language server is running OK. Cheers.