Create grants for altering warehouse sizes (or change the warehouse size to non-mandatory in the yml file)

Describe the feature

The warehouse size is a mandatory information for the validation of the spec-file, however it is not verified to be aligned with the warehouse size on the server and no queries are created in order to align it. So in reality it is only informative and can be misleading if the true size of warehouse is not the same server-side.

I am unsure about enforcing it in Permifrost as maybe some snowflake users change the warehouse sizes for temporary workload, but I guess if it is a mandatory information in the YAML file it should be done.

I think we should either have to:

• create querie to alter the warehouse size (maybe with an optional flag in the permifrost run to change infra and not only roles)
• remove the mandatory aspect of the warehouse size in the YAML (here : src/permifrost/spec_schemas/snowflake.py)

(could be a combination of both)

Additional context

A change in the README.md have been done in this commit about this issue.

Who will this benefit?

It will be beneficial for a better understanding of the project. And if queries are implemented it could be useful to use Permifrost to deal with warehouse sizes.

Are you interested in contributing this feature?

Sure!