Enable CLI access

[darshana-v]

Check the open PRs from javelin-python to merge the changes. Ensure that the CLI interface works correctly for AWS.

[darshana-v]

• Update default authentication url
• Fix header handling to prevent x-api-key conflicts with AISPM routes
  by removing default headers from httpx client initialization
• Add account_id extraction from role_arn for AISPM authentication
• Add AISPM-specific headers (x-javelin-accountid, x-javelin-user, x-javelin-userrole)