Add support for WHEN clause

[paustint]

• Feature
• Bug Request

Description

Add support for WHEN conditions within fields

https://developer.salesforce.com/docs/atlas.en-us.soql_sosl.meta/soql_sosl/sforce_api_calls_soql_select_typeof.htm

SELECT TYPEOF What WHEN Account THEN Phone, NumberOfEmployees WHEN Opportunity THEN Amount, CloseDate ELSE Name, Email END FROM Event