Backport to branch(3) : Add namespace-creation feature

[feeblefakie]

This is an automated backport of the following:

• Original PR: Add namespace-creation feature #322
• Backported commit: 8ad9cca

Please merge this PR after all checks have passed.

[gemini-code-assist]

Summary of Changes

Hello @feeblefakie, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request backports a significant feature that enables the creation of namespaces within the system. It involves a full-stack implementation, from new RPC definitions and client-side service methods to robust server-side logic for managing namespace persistence and validation. The changes ensure that users can programmatically define and utilize isolated environments for their data and contracts, enhancing the system's multi-tenancy and organizational capabilities.

Highlights

• Namespace Creation Feature: This pull request introduces the ability to create namespaces within the system, enabling better organization and isolation of data and contracts.
• API and Client-Side Integration: New RPC methods for createNamespace have been added to LedgerPrivileged, AuditorPrivileged, and GatewayPrivileged services, along with corresponding client-side service methods and handlers to facilitate namespace creation requests.
• Server-Side Logic and Persistence: A new NamespaceManager and NamespaceRegistry have been implemented, backed by ScalarDB, to handle the creation and persistence of namespaces, including the dynamic creation of necessary tables for each new namespace.
• Error Handling and Validation: Several new error codes and status codes related to namespace operations (e.g., INVALID_NAMESPACE_NAME, NAMESPACE_ALREADY_EXISTS) have been introduced, and validation logic ensures proper namespace naming conventions.
• Modular Database Table Management: A TableMetadataProvider interface and its implementations were added to allow different database components (e.g., ScalarTransactionManager, ScalarCertificateRegistry) to declare their required table schemas, which are then used by the NamespaceRegistry to create tables for new namespaces.
• Comprehensive Testing: Extensive unit and integration tests have been added for the new namespace creation functionality, covering various scenarios including valid and invalid inputs, existing namespaces, and retry mechanisms for database operations.

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[gemini-code-assist]

Code Review

This pull request backports the namespace creation feature. The changes are extensive, touching client, server, and common components, and appear to be well-structured. The introduction of TableMetadataProvider and the use of Guice's Multibinder for dynamic table creation is a solid design. The code is clean and includes new tests for the added functionality. I have one suggestion to improve the robustness of the new NamespaceManager.

[gemini-code-assist]

The create method is a public API and should validate its arguments. While the @Nonnull annotation is present, it doesn't provide a runtime guarantee. A null value for namespace would cause a NullPointerException in isValidNamespaceName when matcher(namespace) is called. It's a good practice to add a checkNotNull(namespace) at the beginning of the method to ensure robustness, especially since checkNotNull is already used in the constructor of this class.

For example:

  public void create(@Nonnull String namespace) {
    checkNotNull(namespace);
    if (!isValidNamespaceName(namespace)) {
      throw new LedgerException(CommonError.INVALID_NAMESPACE_NAME, namespace);
    }
    registry.create(namespace);
  }