Handle errors thrown by EL's executePayload

[g11tech]

Motivation
Currently in kintsugi devnets it has been observed that EL throws error like internal error, invalid merkles and sometimes connection refused. There could be host of other scenarios where EL is not able to respond. This causes block to be treated as invalid in the current handling, leading to downscoring of the peers.
In a very limited peer scenario, lodestar eventually kicks all peers and goes out of sync unless peerstore is removed.

This PR

• tracks the EL operation errors separately on executionEngine level and passes the information upstream.
• Where these errors are treated in optimistic scenario allowing CL to move its consensus forward.
• The user is also logged a warn for him to check and take appropriate action/investigation.

and unnecessary/invalid down-scoring of the peer is also prevented.

Closes #3537

[codeclimate]

Code Climate has analyzed commit 2293644 and detected 3 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Complexity	3

View more on Code Climate.

[codecov]

Codecov Report

Merging #3545 (2293644) into master (53f31a7) will decrease coverage by 0.12%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3545      +/-   ##
==========================================
- Coverage   37.56%   37.43%   -0.13%     
==========================================
  Files         310      311       +1     
  Lines        8253     8307      +54     
  Branches     1273     1286      +13     
==========================================
+ Hits         3100     3110      +10     
- Misses       5005     5049      +44     
  Partials      148      148              

[g11tech]

@dapplion reverted the retry mechanism(s). Kindly review.

Would want to tackle the retry mechanism of executionEngine(#3567) in separate PR (along with through review of as how jsonRPC client behaves in various unavailability scenarios) as the aim of this PR is to prevent down-scoring peers because of EL errors.
Local testing (with EL being shutdown) shows that peer count stays good (instead of previous version where it would go to zero)

[g11tech]

Been running locally on kintsugi for an hour+ now with EL shutdown, peer count still strong 25.

[dapplion]

Looks great! Excellent work