match and search flags

[jg-rp]

Add an optional flags argument to the built-in match() and search() filter functions.

This would be a deliberate deviation to the IETF JSONPath standard.

[jg-rp]

Currently, the JSONPath Compliance Test Suite tests for exactly two arguments to match() and search(). I don't particularly want to skip these tests for non-standard versions.

Rather than define optional versions of match() and search(), which accept flags and would need to be added to a custom environment explicitly, we'll suggest people use inline regex group flags.

Closing for now. Please reopen if needed.