Update REST API and DTO layer for new unified RBAC enum

Replace ScopeType/EntityType references with RBACElementType in the REST API and DTO layer:

- api/rbac/scope_adapter.py: Change scope_type parameter to RBACElementType, handle GLOBAL specially (not in RBACElementType)

- api/rbac/entity_adapter.py: Change scope_type/entity_type parameters to RBACElementType, use bridge methods for downstream code

- api/rbac/handler.py: Follows DTO changes automatically

- api/vfolder.py: Direct replacement (ScopeType.PROJECT → RBACElementType.PROJECT, etc.)

- common/dto/manager/rbac/path.py: Change SearchScopesPathParam.scope_type and SearchEntitiesPathParam fields to RBACElementType

- common/dto/manager/rbac/response.py, request.py: Update DTO field types

GLOBAL handling: ScopeType.GLOBAL has no RBACElementType equivalent. scope_adapter.py's GLOBAL branch and SearchScopesPathParam need special handling (Optional or separate flag).

~6 files.

Depends on: BA-4522, BA-4611

JIRA Issue: BA-4612