Implements a "Downscoped credentials" service and use DownScoped tokens in the Delivery service (GONRG-1053, GONRG-1054, GONRG-1055)

Description:

• introduces DownScopedCredentialsService which provides DownScopedCredentials
• uses new service in the GCP StorageServiceImpl to provide DownScoped token as a value of the SignedUrl.connectionString for ovds resources
• introduces split logic for ovds (folder) / non-ovds (blob) resources

How to test:

• Run CICD and check 'StorageServiceImplTest' unit test cases completion results.

Changes include:

• Refactor (a non-breaking change that improves code maintainability).
• Bugfix (a non-breaking change that solves an issue).
• New feature (a non-breaking change that adds functionality).
• Breaking change (a change that is not backward-compatible and/or changes current functionality).

Changes in:

• GCP
• Azure
• AWS
• IBM

Dev Checklist:

• Added Unit Tests, wherever applicable.
• Updated the Readme, if applicable.
• Existing Tests pass
• Verified functionality locally
• Self Reviewed my code for formatting and complex business logic.