Add additional functionality for enterprise budgets

The enterprise budget "Get all budgets" [REST API](https://docs.github.com/en/enterprise-cloud@latest/rest/billing/budgets?apiVersion=2022-11-28#get-all-budgets) supports pagination but the current implementation of the ListBudgets function does not have this functionality in place. Also their is currently no function that corresponds to the "Get a budget by ID" [REST API](https://docs.github.com/en/enterprise-cloud@latest/rest/billing/budgets?apiVersion=2022-11-28#get-a-budget-by-id) endpoint.

I plan to implement the updates myself.