Improve UI/UX related to Call Interceptor Service Policy by supporting an `Enum Array` input type

[ashera96]

Describe your problem(s)

Currently, the Call Interceptor Service policy has an attribute named Includes to Payload. This policy attribute is of type String (refer to [1]). Instead of expecting the user to type in the expected input as a comma-separated list, give an option to select the values from a dropdown menu.

[1] https://github.com/wso2/product-apim/blob/master/modules/distribution/resources/operation_policies/specifications/ccCallInterceptorService_v1.json#L21

Describe your solution

To achieve this we need to introduce a new policy attribute type named Enum Array (right now we only support String, Integer, Boolean, and Enum). With this improvement, the user should be able to select from a list of checkboxes rather than typing in a comma-separated list of values. You can re-use a UI component like so to improve the policy related UI/UX.