[Malleability] Update herocache to use generics and implement BackData.

[AndriiDiachuk]

Context

In this PR Cache and PoolEntity were refactored to use generics enabling them to handle any data type for both the key and the value.

As Cache going to work with flow.Identifier so only V was introduced there.

PoolEntity now uses generic type parameters:

• Key (K) is constrained with comparable, ensuring that it supports equality checks.
• Value (V) is defined as any, allowing flexibility.

This PR is part of the broader refactoring effort referenced in EPIC #6646.

Closes: #7074.

[AndriiDiachuk]

@jordanschalm Hi, I want to ask for your advice. I added wasEjected to the Add function in pool so we can use it instead of the nil comparison, which was before in the put function of the cache. Another option was to return a pointer and not add wasEjected. What do you think is a better option?

[durkmurder]

First batch of comments. Overall all good, can you make sure that Tracer is properly integrated, also can you run lint and ensure tests are passing?

[AndriiDiachuk]

First batch of comments. Overall all good, can you make sure that Tracer is properly integrated, also can you run lint and ensure tests are passing?

Both cache and pool tests are passing. Fixed Tracer implementation as well.