Syntax highlighting is incorrect with # in an alias name

[richb-hanover]

Creating an alias that contains a "#" gives an incorrect coloring in the VSCode Extension. The generated SQL is OK. Using the example below:

from albums
derive `foo#` = 5

In the Playground, the syntax coloring looks OK and the SQL is too.

In the VSCode Extension, the SQL is OK, but the highlighting shows the "#` = 5" to be grey and italicized.

Moved here from: PRQL/prql#4725

[max-sixty]

This would be great to fix. It's probably not a trivial fix given the code grammar is in TextMate, but also not impossible — rust does manage: