builtins: implement numbers.range and range_step

[DFrenkel]

What is the underlying problem you're trying to solve?

Need implementation of numbers.range and numbers.range_step to be used in policies

Expected Outcome

• numbers.range and numbers.range_step can be used in policies
• numbersrange tests pass: https://github.com/open-policy-agent/opa/tree/main/v1/test/cases/testdata/v1/numbersrange