Unsupported builtin languages inside code blocks

[remcohaszing]

VSCode supports the following language IDs by default, but there’s no support for these languages inside markdown code blocks. I think it makes sense to support them.

• hlsl
• ignore
• jsonl
• juliamarkdown
• properties
• raku
• restructuredtext
• shaderlab

The following languages are also unsupported, but I don’t think these should be added, as they are related to VSCode specifics:

• chatmode
• cuda-cpp (Is just C++ I think?)
• dockercompose (Is just YAML)
• instructions
• prompt
• search-result
• snippets (Is just JSONC)