Feature request: allow PHPDeserialize to decode objectcode and references

**Is your feature request related to a problem? Please describe.**
the current php deserialiser will error out of a block contains an object or reference

**Describe the solution you'd like**
decode the data to a partial state with dummy objects

**Additional context**
Ive made a PR for this already but it has not been reviewed
https://github.com/gchq/CyberChef/pull/2046

Start by reviewing the existing implementation in PR #2046, since the issue says the work is already proposed there. Check how PHPDeserialize handles blocks containing objectcode or references, and confirm that the completed behavior decodes a partial state using dummy objects without errors.

Written by the indexing model from the issue text.