Solve slowness in otterize clientintents export by namespaces caused by slow query for list of namespaces, by using minimal GraphQL API query for namespaces fields

[amitlicht]

Description

This PR slows delays in otterize clientintents export --namespaces <namespacename>, caused due to slow querying of the list of namespaces which is needed to resolve namespace name to ID.
This is resolved by using a minimalized gql-based query for namespaces resolving purpose, where only the namespace names & IDs and cluster names & IDs are queried (rather than full namespace & cluster info).

References

• See the Otterize API docs for references re our REST APIs & GraphQL APIs

Testing

• This change adds test coverage for new/changed/fixed functionality

Checklist

• I have added documentation for new/changed functionality in this PR and in github.com/otterize/docs