Mux: Single peer performance for Leios

## Why

See https://github.com/input-output-hk/ouroboros-leios/issues/544#issue-3398692866

We need to prioritize Praos > Leios (and slightly less important: fresh Leios > stale Leios). With near certainty, Praos and Leios traffic will be implemented using two separate mini protocols. Hence, we want to limit the impact one mini-protocol can have on the other and further explore options how to **improve single peer performance**.

## What

* [x] #5261 will allow us to independently of the consensus demo validate early implementations, later on it can serve as a basis for writing proper tests, and eventually give us data points to initially configure mux with Leios capabilities, which later can be validated using the consensus Leios demo.
* [x] #5271
* [x] #5262 we will explore prioritisation of egress queues to support Leios design requirement to prioritise Praos traffic over Leios traffic. It will be early-validated using #5261 and later on using the consensus Leios demo.
* [ ] #5263 we will explore dynamic egress rate limiting. It will be early-validated using #5261 and later on using the consensus Leios demo.
* [x] For prioritisation of fresh Leios traffic over stale Leios traffic, we plan to do server-side reordering. An early idea was explored in input-output-hk/ouroboros-leios#638.
* [ ] #5280: incremental decoding experiment based on `cardano-diffusion:demo-chain-sync` to measure possible performance gains from using incremental cbor decoding