Added merge_workload and mutation_workload settings for resource regulation

Why it matters

These new settings address the challenge of balancing resource usage among different internal operations, allowing users to better regulate how CPU and IO resources are distributed between merges, mutations, and other concurrent workloads. This helps optimize performance and prevents resource contention, improving overall system efficiency.

How to use it

Users can enable and configure resource sharing by setting merge_workload and mutation_workload parameters in their server or session configuration files. Adjust these settings according to workload priorities to fine-tune resource allocation between merges, mutations, and other queries.