Send acknowledge/modifyAckDeadline requests in chunks

[ctavan]

The acknowledge and modifyAckDeadline API requests seem to have a size
limitation: If you send to many ackIds with one request you may get the
following error:

Request payload size exceeds the limit: 524288 bytes.

In order to prevent this error, make sure to always send those requests
in chunks that are small enough.

Fixes #62.

• Tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

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[codecov]

Codecov Report

Merging #65 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #65   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           8      8           
  Lines         845    849    +4     
=====================================
+ Hits          845    849    +4

Impacted Files	Coverage Δ
src/subscription.js	100% <100%> (ø)	⬆️

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[googlebot]

CLAs look good, thanks!

[ctavan]

I'm happy to add test-cases to cover the chunking once we agree on an implementation.

[callmehiphop]

@ctavan overall I think this LGTM, did this solve your issue? Any thoughts here @stephenplusplus?

[stephenplusplus]

Looks okay to me. Did anyone try the system tests?

[ctavan]

@callmehiphop @stephenplusplus I have not seen the error reported in #62 since running with this patched code while I was getting the error on the majority of service restarts before: So I'm pretty confident that it does what it's supposed to :).

Also, we've been running this in production for the last 4 days without any issues. Restarts of our services now no longer produce duplicates that we got due to failed acknowledge requests during service shutdowns.

[ctavan]

Oh, I've also added 4 test cases for acknowledge_/modifyAckDeadline_ for the streaming/non-streaming cases respectively which cover the chunking behavior.

Would be great if this would land in the next release!

[callmehiphop]

@ctavan looks like our lint task is failing - if you would be so kind as to run npm run prettier, I think that should fix it!

[ctavan]

@callmehiphop whoops, I should have checked linting, sorry for the additional loop.

Should be better now.

[callmehiphop]

@ctavan no worries! I went ahead and ran all the system tests locally and they're all green, so I think we're good to go. Thanks again for the contribution!