runtime(typst): Improve ftplugin, and syntax file

runtime(typst): Improve ftplugin, and syntax file

- Move whitespace formatting settings from the indent to the filetype
  plugin behind a "typst_recommended_style" config option.
- Set browsefilter
- Improve syntax file

Thanks to Maxim Kim for taking on maintainership of the typst runtime
files.

related: #20036
closes:  #20077

Co-authored-by: Maxim Kim <habamax@gmail.com>
Signed-off-by: Maxim Kim <habamax@gmail.com>
Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>