feat(p2p): channel enqueue timeout and improved router cleanup

[lklimek]

Issue being fixed or feature implemented

Channels are blocking when number of queued items is too big. We need a way to reject further messages sent to these channels.

What was done?

1. Introduced enqueue timeout
2. Refactored router to better handle cleanups.
3. Added config option [mempool] tx-enqueue-timeout

How Has This Been Tested?

On ouzo devnet + added unit test

Breaking Changes

None

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have made corresponding changes to the documentation

For repository code-owners and collaborators only

• I have assigned this pull request to a milestone

[shumkov]

👍