Propagate Log Update Failures in AddSequencedLeaves

[therealdrake]

AddSequencedLeaves in the log client previously did not evaluate the response proto. Adding some fail case checking and logging.

[codecov]

Codecov Report

Merging #1544 (735f1dd) into master (5e12fb3) will increase coverage by 1.12%.
The diff coverage is 0.00%.

❗ Current head 735f1dd differs from pull request most recent head 6458c64. Consider uploading reports for the commit 6458c64 to get more accurate results

@@            Coverage Diff             @@
##           master    #1544      +/-   ##
==========================================
+ Coverage   66.12%   67.24%   +1.12%     
==========================================
  Files         103      105       +2     
  Lines        7013     8586    +1573     
==========================================
+ Hits         4637     5774    +1137     
- Misses       1884     2230     +346     
- Partials      492      582      +90     

Impacted Files	Coverage Δ
client/log_client.go	68.89% <0.00%> (-9.40%)	⬇️
storage/mysql/queue.go	43.13% <0.00%> (-19.61%)	⬇️
trees/optype_string.go	16.66% <0.00%> (-16.67%)	⬇️
quota/group_string.go	22.22% <0.00%> (-11.12%)	⬇️
quota/kind_string.go	25.00% <0.00%> (-8.34%)	⬇️
client/log_verifier.go	71.92% <0.00%> (-8.08%)	⬇️
quota/quota.go	85.71% <0.00%> (-5.96%)	⬇️
crypto/keys/handlers.go	83.33% <0.00%> (-4.91%)	⬇️
storage/mysql/tree_storage.go	49.26% <0.00%> (-4.25%)	⬇️
... and 137 more

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[gdbelvin]

Thanks for submitting this much needed change.
Just a few suggestions on using the status library for easier handling of the status

I'll also loop in @Martin2112 for his approval.

[AlCutter]

wdyt @Martin2112 ?

[gdbelvin]

Approving.

@Martin2112 FYI

[Martin2112]

It looks like the client doesn't get to find out which leaves already exist. Maybe that doesn't matter.

[mhutchinson]

/gcbrun

[mhutchinson]

/gcbrun