[MOB-7936] create iterable embedded placement class

[evantk91]

🔹 JIRA Ticket(s) if any

• MOB-7936

✏️ Description

This pull request creates the IterableEmbeddedPlacement class and associated child classes. Each child class has its own constructor and fromDict function for converting from a dictionary into the associated javascript object. Each child class also has an associated test suite to test conversions and error handling.