Arbitatrary validation written in javascript

[mattyg]

Expands on / alternative to #3

AC

• I can create an entry EntryTypeValidation that includes:
  • name: String
  • 3 strings containing javascript functions for validate create, validate update, validate delete
• Include a javascript interpreter in our Generic DNA
• Validation serializes the rust types to json, passes them as inputs to the js functions and uses the response to return a validation result

Possible JS interpreters:

• https://github.com/boa-dev/boa