sdk: fix fromEthersEvent ranges fetching in case of temporary connectivity loss

[andrevmatos]

Fixes #1923
Follow-up of #1832

Short description
This PR fixes the issue by using a fromBlock queue, instead of a single value, so we always keep track of "[range] successful requests in the past", and can proceed with the correct ranges even in case of connectivity loss or exceptions thrown.
Also, the queue is only walked over (i.e. popping the front we just queried, pushing to the back the new block for future range request) if the request didn't throw, allowing us to safely ignore any network error/exception thrown while scanning ranges and retrying the previous fromBlock when a new block event is emitted, which indicates connectivity was restored.

Definition of Done

• Steps to manually test the change have been documented
• Acceptance criteria are met
• Change has been manually tested by the reviewer (dApp)

Steps to manually test the change (dApp)

1. Disconnect the browser from internet while dApp is connected and monitoring some channel/tokenNetwork
2. Do some transaction which would show up on an event (e.g. a deposit on partner)
3. Wait more than 5 blocks after transaction, then connect back to internet
4. See event got picked up properly, network failures didn't error/shutdown the SDK

[codecov]

Codecov Report

Merging #1924 into master will decrease coverage by 0.13%.
The diff coverage is 93.75%.

@@            Coverage Diff             @@
##           master    #1924      +/-   ##
==========================================
- Coverage   95.74%   95.61%   -0.14%     
==========================================
  Files         155      155              
  Lines        5809     5816       +7     
  Branches     1094     1095       +1     
==========================================
- Hits         5562     5561       -1     
- Misses        189      197       +8     
  Partials       58       58              

Flag	Coverage Δ
#dapp	91.82% <ø> (ø)
#sdk	97.19% <93.75%> (-0.20%)	⬇️
#sdk_e2e	65.71% <93.75%> (+0.18%)	⬆️
#sdk_integration	?
#sdk_unit	86.37% <93.75%> (-0.03%)	⬇️

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Impacted Files	Coverage Δ
raiden-ts/src/utils/ethers.ts	97.53% <93.75%> (-1.12%)	⬇️
raiden-ts/src/polyfills.ts	71.42% <0.00%> (-28.58%)	⬇️
raiden-ts/src/raiden.ts	91.52% <0.00%> (-0.25%)	⬇️

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[weilbith]

I need a call for this. The queue functionality is not clear to me. Sorry 😑

[weilbith]

We had a pretty good call together. This algorithm is much more complex and beautiful than I initially thought. I had some misconceptions in my mind. Thanks for helping me out. Now I'm confident that is a really good fix!! 🚀