added newrelic close buffer

[armstrmi]

Description of Changes

• Added close buffer functionality newrelic
• Added tests to test buffer functionality

  Please check that the PR fulfills these requirements

• [ ] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been added / updated (for bug fixes / features)
• [ ] Add a changelog entry (for non-trivial bug fixes / features)
• [ ] CI passes

[codecov[bot]]

Codecov Report

Merging #577 (1d48d5f) into buffer-rework (78623d8) will increase coverage by 5.30%. The diff coverage is 85.40%.

@@                Coverage Diff                @@
##           buffer-rework     #577      +/-   ##
=================================================
+ Coverage          67.50%   72.80%   +5.30%     
=================================================
  Files                 61       75      +14     
  Lines               3886     5585    +1699     
=================================================
+ Hits                2623     4066    +1443     
- Misses              1060     1279     +219     
- Partials             203      240      +37     

Impacted Files	Coverage Δ
operator/buffer/buffer.go	75.86% <ø> (-1.92%)	:arrow_down:
...builtin/input/aws/cloudwatch/cloudwatch_persist.go	62.50% <ø> (-8.93%)	:arrow_down:
operator/builtin/input/azure/event_hub.go	0.00% <ø> (ø)
operator/builtin/input/azure/event_hub_config.go	90.91% <ø> (-1.09%)	:arrow_down:
operator/builtin/input/file/finder.go	100.00% <ø> (ø)
operator/builtin/input/file/reader.go	53.05% <0.00%> (-5.73%)	:arrow_down:
operator/builtin/input/http/config.go	97.03% <ø> (-0.23%)	:arrow_down:
operator/builtin/input/journald/journald.go	57.06% <ø> (-2.03%)	:arrow_down:
operator/builtin/output/googlecloud/severity.go	100.00% <ø> (+72.73%)	:arrow_up:
operator/helper/persist/cached_persister.go	100.00% <ø> (ø)
... and 88 more

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[BinaryFissionGames]

The windows unit test failure is interesting, https://github.com/golang/go/issues/22553 - may or may not be related to this pr, I'd be a little surprised if it was related, though.