Add API for getting a diff of a specific file

[nitzan-entro]

Feature Description

Currently the commit diff api is for the whole commit content and not by files in the commits, but after looking at impl of diff api the part that gets the diff accepts also a file name, it will be really simple to add the file name to the same api as optional parameter or add another endpoint.

Screenshots

No response

[nitzan-entro]

Didnt really get how i can contribute code here, but if someone can merge this for it'll be delightful :)

added_an_option_to_get_a_single_file_diff_api_query_param.patch

[nitzan-entro]

@kemzeb can u assist?