Update regex and logic for snippet capturing

[franciszekjob]

Which components does the task require to be changed? (think hard pls)

other

Description

Currently, snippets are captured by regex which should start with $ snforge/sncast .... However, this doesn't allow for other cases, e.g.

$ SNFORGE_BACKTRACE=1 snforge test

Snippets capturing and internal logic could be possibly reworked to allow such cases.

[petersdt]

@cptartur @franciszekjob can i jump on this

[franciszekjob]

Hey @petersdt , thanks for applying, however we mostly accept applications for tasks marked with "help wanted" or "good first issue" label.