Sync first epoch duration at application startup

[alexvanin]

Closes #679

At the startup, Inner Ring application calculates block duration before next epoch tick and processes new epoch event at this block.

[codecov]

Codecov Report

Merging #708 (a75fe73) into master (dfbde00) will increase coverage by 0.06%.
The diff coverage is 88.88%.

❗ Current head a75fe73 differs from pull request most recent head 6e0a141. Consider uploading reports for the commit 6e0a141 to get more accurate results

@@            Coverage Diff             @@
##           master     #708      +/-   ##
==========================================
+ Coverage   44.30%   44.37%   +0.06%     
==========================================
  Files         211      211              
  Lines        9688     9700      +12     
==========================================
+ Hits         4292     4304      +12     
- Misses       5043     5044       +1     
+ Partials      353      352       -1     

Impacted Files	Coverage Δ
pkg/morph/client/client.go	11.33% <0.00%> (-0.16%)	⬇️
pkg/morph/timer/block.go	97.26% <100.00%> (+3.60%)	⬆️

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[alexvanin]

To process single event in the future, I added NewOneTickTimer constructor in morph/timer (4ab91ae). Maybe there is a better solution for this.

[carpawell]

it took some time for me to get the idea of what EpochBlock returns, i had to go to read it in contract code
wouldn't it be better to add smth like "last" or "start" or both to the method name?

[alexvanin]

wouldn't it be better to add smth like "last" or "start" or both to the method name?

I thought about that. LastEpochBlock() in the contract and in the code will be better, what do you think?

[carpawell]

what do you think?

yes, it sounds better for me