Reduce the amount of escaping in typst math writer

**Describe your proposed improvement and the problem it solves.**

When translating simple expressions like:

```
$r_i(c, c_M)$
```

the writer adds a lot of seemingly unnecessary escape sequences to parentheses and commas:

```
$r_i \( c \, c_M \)$
```

Probably this simplify the code and/or ensure against some corner cases that I can't think of, but it certainly clutters the code which can be an inconvenience for progressive markdown -> typst approaches.