Ignore numbering pattern string in Typst functions

## Description

```typ
#set heading(numbering: "I-I.")
Some text
```

Gives "Did you mean to spell `I.` this way?"

This doesn't happen with no text or only one word. Since [numbering](https://typst.app/docs/reference/model/numbering/) can have a pattern string, it makes no sense to check it for errors and should be just skipped.

## Resources

## Screenshots

Reproduce the issue with the provided Typst heading and numbering pattern, then trace how the `numbering` setting is checked when text contains multiple words. The change is done when pattern strings such as `"I-I."` are skipped and no spelling warning is emitted, while the existing checks remain for ordinary text.

Written by the indexing model from the issue text.