[FEATURE] Chainable if/then else if/then else

[beeme1mr]

Requirements

JsonLogic supports chainable if/then else if/then logic. This can simplify how complex conditionals can be represented in a targeting rule. It should be supported by all spec-compliant JsonLogic implementations.

Tasks

Beta Give feedback

1. Update the JSON schema to support 3 or more arguments flagd-schemas#137
   +0
2. Update the flagd documentation to include examples of an else if condition
3. Update the playground examples to no longer use nested if conditions.

This is a follow-up to this issue.