Refractor update_mempool module in JDS mempool module for simplified async flow

[NonsoAmadi10]

What does this PR do?

Closes #784

• Removed the unnecessary use of tokio::task::spawn in update_mempool, leveraging the existing async function context for all operations.
• Removed the TokioJoin(JoinError) implementation since it is not been used

[NonsoAmadi10]

@GitGab19 I have re-reviewed and made some changes here, please I am requesting a review here and also to point out that the MG test is still failing

[GitGab19]

@GitGab19 I have re-reviewed and made some changes here, please I am requesting a review here and also to point out that the MG test is still failing

I would ask to @lorbax to have a look at this, since he opened issue #784 and he worked on the async management during last release 🙏

[lorbax]

I will do it by the next week!

[lorbax]

This is a good PR
I would be good to have the minor changes that I left as comments

[NonsoAmadi10]

@lorbax i have been able to manage the unhappy paths in the the update_mempool function, please I request your feedback on this before I pick up the next issue. Thanks

[plebhash]

@NonsoAmadi10 can you rebase?

[NonsoAmadi10]

Alright I am on it

[NonsoAmadi10]

I have rebased. cc: @plebhash @lorbax

[plebhash]

@lorbax once you do the final review here, are you able to approve?

[Fi3]

This PR needs to be rebased on dev

[GitGab19]

LGTM.
@lorbax could you double check when you get a chance pls?

[lorbax]

@NonsoAmadi10 you must also remove the TokioJoin variant of JdsMempoolError

[Fi3]

The right pattern to follow when we implement a variant that is only a container for an error that come from a library is to implement From for the error like here:

https://github.com/stratum-mining/stratum/blob/main/roles/jd-server/src/lib/error.rs#L55

[lorbax]

Run local TP, pool, jds, jdc, tproxy and cpuminer without issues.
The code looks good to me.