Log failure to find the associated language tree-sitter grammar

[kirawi]

When users report not having syntax highlighting, this is usually (if not always) because the compiled language grammars are not present in their runtime/grammars folder. We should log an error in this case. This is probably as simple as .map_err() on a Result somewhere in helix-view/src/document.rs like in #746.

[archseer]

It's valid to define a new language without a matching tree-sitter grammar though (let's say if you have a LSP but no grammar). If we do log it, it should probably be a debug level log.