Missing feature: Templates highlighting (currently a syntax error)

[shawwn]

Lark templates currently show up as syntax errors:

e.g.

sep{item, delim}: item (delim item)*

[Stehlampe2020]

I may spend some time soon to get this implemented myself and then I'll do a PR if I deem my code acceptable.
I heavily use templates in my own programming language (for e.g. arrow-separated lists of instructions), so right now I need to manually be able to distinguish between the LARK plugin not understanding templates and actual syntax errors in my LARK syntax. And the "98" in theerror count is right now just it not understanding templates, as lark itself doesn't complain about anything in my syntax.