Support max length for array and map

[dselman]

Feature Request 🛍️

Extend the metamodel to support validation facets for the length of an array and the number of keys in a map.

Use Case

Allows the model to define the maximum number of elements in array or map.

Possible Solution

1. Update metamodel
2. Update CTO grammar and parser
3. Update AST printer
4. Update validation

Context

Detailed Description

[apoorvsxna]

For the max number of keys in a map, here's an example of the syntax I'm thinking of-

map m {
  o String
  o Integer
  -> maxKeys = 3
}

Do let me know if the syntax should be different.