fix(agent): fix mongodb instrumentation for PHP 8.0+

[bduranleau-nr]

• split mongodb instrumentation into before/after inline with OAPI paradigm.
• remove broken integration tests in favor of Multiverse tests

[newrelic-php-agent-bot]

Test Suite	Status	Result
Multiverse	✅	/ passing
SOAK	❌	/ passing

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 61 lines in your changes missing coverage. Please review.

Please upload report for BASE (dev@756c1aa). Learn more about missing BASE report.

Files	Patch %	Lines
agent/lib_mongodb.c	0.00%	54 Missing ⚠️
agent/php_wrapper.c	0.00%	7 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff           @@
##             dev     #878   +/-   ##
======================================
  Coverage       ?   78.57%           
======================================
  Files          ?      193           
  Lines          ?    27290           
  Branches       ?        0           
======================================
  Hits           ?    21443           
  Misses         ?     5847           
  Partials       ?        0           

Flag	Coverage Δ
agent-for-php-7.0	77.49% <0.00%> (?)
agent-for-php-7.1	77.24% <0.00%> (?)
agent-for-php-7.2	78.16% <0.00%> (?)
agent-for-php-7.3	78.18% <0.00%> (?)
agent-for-php-7.4	77.89% <0.00%> (?)
agent-for-php-8.0	77.92% <0.00%> (?)
agent-for-php-8.1	77.90% <0.00%> (?)
agent-for-php-8.2	77.50% <0.00%> (?)
agent-for-php-8.3	77.50% <0.00%> (?)

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[lavarou]

I have a few questions:

• https://github.com/newrelic/newrelic-php-agent/pull/878/files#r1600397303
• https://github.com/newrelic/newrelic-php-agent/pull/878/files#r1600405720
• https://github.com/newrelic/newrelic-php-agent/pull/878/files#r1600265944

And one suggestion:

• https://github.com/newrelic/newrelic-php-agent/pull/878/files#r1600264589

[zsistla]

Great job getting this working.