feature: Make the scheduler policy actually pluggable

Thanks for taking the time to suggest an improvement.

## Problem statement
Today we have single entry point to call the scheduling heuristic from a ron config file. The generic schduler bundled today is ok but for some more advance application users might want to override that manually (or automatically)

## Proposed solution

Not sure yet. Maybe in the Ron file itself we could point to a structure. We need to think about how we can pass parameters and existing logs (for more advance use cases like PGO) as a input

## Alternatives considered (optional)

## Impact / scope (optional)
- Affected crates, platforms, or features:

## Additional context (optional)

Start by locating the scheduler entry point called from a Ron config file and trace how the bundled generic scheduler receives configuration. The design needs to establish how a policy can be selected or overridden and how parameters and existing logs can be supplied; done means the approach is documented and the scheduler policy is genuinely pluggable.

Written by the indexing model from the issue text.