CSL short title support

[pjtsearch]

Description

CSL has an option for short titles that is used, for example, in the chicago-note format:

...
<text variable="title" text-case="title" form="short" font-style="italic" />
...

Right now, Typst uses the BibTex title field for the CSL short title, but BibTex also has a field shorttitle that should be used instead. Ex.

@book{mchugo_syria_2015,
  title = {Syria: {{A History}} of the {{Last Hundred Years}}},
  shorttitle = {Syria: {{A History}}},
  author = {McHugo, John},
  year = {2015},
  publisher = {The New Press},
  address = {New York},
  urldate = {2023-01-09},
  isbn = {978-1-62097-045-4},
  langid = {english},
  keywords = {syria}
}

Thus, instead of looking like this:

It would look like this:

Use Case

This feature would be useful to users who use the chicago-note style or other CSL styles that use the short title.

[reknih]

Closed in #174