Serverless mode [DO NOT MERGE]

[obenkenobi]

### Overview
Introduces serverless mode for the agent as according to the agent spec.

Todo: include details about how these changes work.

Related Github Issue

#2704

[codecov-commenter]

Codecov Report

❌ Patch coverage is 82.29508% with 108 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.71%. Comparing base (24d16c2) to head (e28e665).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
...a/com/newrelic/agent/ServerlessHarvestService.java	66.44%	43 Missing and 7 partials ⚠️
...transport/serverless/DataSenderServerlessImpl.java	84.46%	14 Missing and 2 partials ⚠️
...t/src/main/java/com/newrelic/agent/RPMService.java	54.54%	9 Missing and 1 partial ⚠️
...ent/transport/serverless/ServerlessWriterImpl.java	33.33%	8 Missing ⚠️
...wrelic/agent/serverless/ServerlessServiceImpl.java	75.00%	4 Missing ⚠️
.../src/main/java/com/newrelic/agent/Transaction.java	0.00%	2 Missing and 1 partial ⚠️
...ava/com/newrelic/agent/trace/TransactionTrace.java	25.00%	2 Missing and 1 partial ⚠️
...ic/agent/transport/serverless/TelemetryBuffer.java	98.49%	0 Missing and 3 partials ⚠️
...om/newrelic/agent/config/ServerlessConfigImpl.java	88.88%	2 Missing ⚠️
...ent/introspec/internal/IntrospectorRPMService.java	0.00%	1 Missing ⚠️
... and 8 more

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2796      +/-   ##
============================================
+ Coverage     70.01%   70.71%   +0.69%     
- Complexity    10520    10534      +14     
============================================
  Files           872      877       +5     
  Lines         43070    42602     -468     
  Branches       6608     6439     -169     
============================================
- Hits          30157    30124      -33     
+ Misses        10010     9578     -432     
+ Partials       2903     2900       -3     

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