Refactor: `subprotocols` crates

[GitGab19]

This task is an outcome of the protocols Rust docs issues tracked in #845.

While documenting protocols::v2::subprotocols in #1201, areas of potential code debt were identified. This issue servers as a place to list out these items to then be addressed in an organized manner. The initial Rust documentation effort was an immediate action, while a refactoring (which implies breaking API changes) is not so urgent priority, so for now we should leave this in the backlog for an appropriate moment in the future.

Identified Potential Code Debt

TODO

[Shourya742]

common_message_sv2: https://github.com/stratum-mining/stratum/pull/1242#issuecomment-2490729166

[Shourya742]

common_message_sv2: https://github.com/stratum-mining/stratum/pull/1242#discussion_r1851827737

[Shourya742]

common_message_sv2: https://github.com/stratum-mining/stratum/pull/1242#discussion_r1851851553

[Shourya742]

template-distribution: https://github.com/stratum-mining/stratum/pull/1257#discussion_r1852013899

[Shourya742]

template-distribution: https://github.com/stratum-mining/stratum/pull/1257#discussion_r1852014658

[Shourya742]

template-distribution: https://github.com/stratum-mining/stratum/pull/1257#discussion_r1852331612

[Shourya742]

template-distribution: https://github.com/stratum-mining/stratum/pull/1257#discussion_r1852416791

[jbesraa]

One of the key things I think we are missing in the subprotocols is how to actually use them.

For example, there is no explanation how to connect to a pool and open SV2 compatible channel. Or simpler, how do I connect to a template provider.

For us this stuff is intuitive and we have roles crates as reference but I actually think the main reference should be in the subprotocols crates.