Serializable Subgrounds Queries

**Is your feature request related to a problem? Please describe.**
I would like to build my queries and execute them separately.

**Describe the solution you'd like**
Serializable queries

**Describe alternatives you've considered**
Saving queries as code and running it separately

**Additional context**
- Serializing synthetic fields will require pickle (or dill to be safer)
- Technically, this is arbitrary code execution so by default, Synthetic support would be off with a flag to turn it on (and a warning).
- This would either happen on-save **and** on-load (with flags and warnings in appropriate locations).

**Implementation checklist**
- [ ] Task 1

Look at the Subgrounds query building and execution code to understand the current query representation. Investigate serialization methods (pickle/dill) and how to safely handle synthetic fields. Determine where to add serialization/deserialization logic and the flag for enabling synthetic field support.

Written by the indexing model from the issue text.