Improve k8 agent integration

[anthony-grasso-datastax]

• Moved calls to Astra DevOps API out of credentials and into client
  • Created functions to create and delete a token in Astra
• Changed the way token life cycle is managed
  • Removed renewal_time from config path and lease_time from credentials path
  • Added ttl and max_ttl to role where they are used during token renewal as part of the response
• Changed how token data is stored locally
  • Calculate a unique token hash based on OrgId, RoleName, and LogicalName
  • Use unique token hash to save, retrieve, and delete token from local storage
• Added sidecar mode
  • Added caller_mode switch to config path to allow sidecar mode to be enabled
  • In sidecar mode read and update are identical, and create a new token when called
  • In sidecar mode the token's clientId is used to save the token in local storage
  • In sidecar mode logical_name is ignored when calling the org/token path

Todo:

• [x] Update tests
• [x] Remove debug code
• [x] Update logging
• [x] Update documentation/README
• [x] Bump version
• [x] Squash commits and rebase on main branch