Parse (import) more expression formats

[jakeboone02]

• Parse CEL #323
• Add parseMongoDB #392
• Add parseJsonLogic #320
• v7 final prep #663 adds parseSpEL

For MongoDB and JsonLogic, JSON.parse the first argument if it's a string.

Research: Do any of these have publicly-available AST specs like SQL? (Probably not necessary for JsonLogic and MongoDB since they're already well structured.)

• CEL / language definition
• SpEL AST spec / source code
• MongoDB operator list

Other (unlikely) possibilities

• Cypher
• SPARQL (sparqljs)
• JQL (can this use case be covered by the SQL export?)