Add "be set" and "not be set" operators to lead/custom object check steps

[iamEAP]

Problem / Motivation

Sometimes, we may want to assert that a lead field was set, but without specifying a value that it was set to. This is especially useful in cases where field values are expected, but set in only a semi-deterministic way (e.g. a round-robin style assignment).

Scope / UAT Target

• Lead check step
  • The expectation field on LeadFieldEqualsStep should be optional
  • The step should result in an error (An expected field value must be provided) if no expectation was provided, and the operator was anything other than be set or not be set.
  • The step expression for LeadFieldEqualsStep should be updated to the (?<field>[a-zA-Z0-9_-]+) field on marketo lead (?<email>.+) should (?<operator>be less than|be greater than|be set|be|contain|not be set|not be|not contain) ?(?<expectation>.+)?
• Custom Object check step
  • The expectedValue field on CustomObjectFieldEqualsStep should be optional
  • The step should result in an error (An expected field value must be provided) if no expectedValue was provided, and the operator was anything other than be set or not be set.
  • The step expression for CustomObjectFieldEqualsStep should be updated to the (?<field>[a-zA-Z0-9_-]+) field on the (?<name>.+) marketo custom object linked to lead (?<linkValue>.+) should (?<operator>be less than|be greater than|be set|be|contain|not be set|not be|not contain) ?(?<expectedValue>.+)?

Depends on run-crank/typescript-cog-utilities#14