[sampler-xray]Added AWS X-Ray Sampler implementation

[AsakerMohd]

Description:

Currently, there isn't any implementation of the AWS X-Ray Remote Sampler that allows customers to fetch their sampling rules and sample accordingly. This PR adds the implementation for that sampler. The customer is able to configure their sampling rules through AWS CloudWatch: https://docs.aws.amazon.com/xray/latest/devguide/xray-console-sampling.html. This implementation fetches the sampling rules using a set polling interval which is set when creating a new instance of AWSXRayRemoteSampler. This implementation is based on similar sampler implementations in other OTEL languages.

• .NET for example: https://github.com/open-telemetry/opentelemetry-dotnet-contrib/tree/main/src/OpenTelemetry.Sampler.AWS

The sampling rule has two components: a reservoir and a fixed sampling rate. The idea here is once the sampling rule is matched and the reservoir is exhausted, the spans are sampled at a fixed rate according to their trace ids. As a result, the remote sampler samples the spans using two samplers: A reservoir sampler and a fixed rate sampler and chooses which one according to the reservoir quota.

Testing:

Unit Testing:

Wrote unit tests for the major classes to assert for correctness and they're all passing.

Manual Testing:

Wrote a sample app with manual instrumentation and hooked up the X-Ray Sampler to the Tracer. I then verified that requests are being sampled as expected using different sampling rules.

[codecov]

Codecov Report

❌ Patch coverage is 78.23344% with 69 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.05%. Comparing base (30ed261) to head (b222507).
⚠️ Report is 22 commits behind head on main.

Files with missing lines	Patch %	Lines
src/Sampler/Xray/src/AWSXRayRemoteSampler.php	66.17%	23 Missing ⚠️
src/Sampler/Xray/src/RulesCache.php	59.18%	20 Missing ⚠️
src/Sampler/Xray/src/SamplingRuleApplier.php	91.75%	8 Missing ⚠️
src/Sampler/Xray/src/FallbackSampler.php	30.00%	7 Missing ⚠️
src/Sampler/Xray/src/RateLimitingSampler.php	25.00%	6 Missing ⚠️
src/Sampler/Xray/src/Matcher.php	81.25%	3 Missing ⚠️
src/Sampler/Xray/src/SamplingRule.php	71.42%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #405      +/-   ##
============================================
+ Coverage     79.35%   83.05%   +3.70%     
- Complexity     1262     1517     +255     
============================================
  Files           109      108       -1     
  Lines          5434     5997     +563     
============================================
+ Hits           4312     4981     +669     
+ Misses         1122     1016     -106     

Flag	Coverage Δ
Aws	93.41% <ø> (+0.82%)	⬆️
Context/Swoole	0.00% <ø> (ø)
Exporter/Instana	49.42% <ø> (ø)
Instrumentation/AwsSdk	81.13% <ø> (ø)
Instrumentation/CakePHP	20.40% <ø> (ø)
Instrumentation/CodeIgniter	73.98% <ø> (+0.43%)	⬆️
Instrumentation/Curl	87.66% <ø> (-2.77%)	⬇️
Instrumentation/Doctrine	92.92% <ø> (ø)
Instrumentation/ExtAmqp	88.48% <ø> (ø)
Instrumentation/ExtRdKafka	86.11% <ø> (ø)
Instrumentation/Guzzle	75.58% <ø> (ø)
Instrumentation/HttpAsyncClient	78.04% <ø> (ø)
Instrumentation/IO	70.68% <ø> (ø)
Instrumentation/Laravel	?
Instrumentation/MongoDB	?
Instrumentation/MySqli	95.81% <ø> (ø)
Instrumentation/OpenAIPHP	87.21% <ø> (?)
Instrumentation/PDO	94.21% <ø> (ø)
Instrumentation/PostgreSql	93.54% <ø> (?)
Instrumentation/Psr14	76.47% <ø> (ø)
Instrumentation/Psr15	89.15% <ø> (ø)
Instrumentation/Psr16	97.50% <ø> (ø)
Instrumentation/Psr18	77.46% <ø> (ø)
Instrumentation/Psr3	67.01% <ø> (ø)
Instrumentation/Psr6	97.61% <ø> (?)
Instrumentation/ReactPHP	99.45% <ø> (ø)
Instrumentation/Slim	86.11% <ø> (ø)
Instrumentation/Symfony	84.88% <ø> (ø)
Instrumentation/Yii	77.86% <ø> (?)
Logs/Monolog	100.00% <ø> (ø)
Propagation/CloudTrace	89.77% <ø> (?)
Propagation/Instana	98.11% <ø> (?)
Propagation/ServerTiming	100.00% <ø> (?)
Propagation/TraceResponse	100.00% <ø> (ø)
ResourceDetectors/Azure	91.66% <ø> (ø)
ResourceDetectors/Container	93.02% <ø> (?)
ResourceDetectors/DigitalOcean	100.00% <ø> (?)
Sampler/RuleBased	33.51% <ø> (ø)
Sampler/Xray	78.23% <78.23%> (?)
Shims/OpenTracing	92.45% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/Sampler/Xray/src/AWSXRaySamplerClient.php	100.00% <100.00%> (ø)
src/Sampler/Xray/src/RateLimiter.php	100.00% <100.00%> (ø)
...rc/Sampler/Xray/src/SamplingStatisticsDocument.php	100.00% <100.00%> (ø)
src/Sampler/Xray/src/SamplingRule.php	71.42% <71.42%> (ø)
src/Sampler/Xray/src/Matcher.php	81.25% <81.25%> (ø)
src/Sampler/Xray/src/RateLimitingSampler.php	25.00% <25.00%> (ø)
src/Sampler/Xray/src/FallbackSampler.php	30.00% <30.00%> (ø)
src/Sampler/Xray/src/SamplingRuleApplier.php	91.75% <91.75%> (ø)
src/Sampler/Xray/src/RulesCache.php	59.18% <59.18%> (ø)
src/Sampler/Xray/src/AWSXRayRemoteSampler.php	66.17% <66.17%> (ø)

... and 45 files with indirect coverage changes

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[brettmc]

Please add .gitsplit config so it can be published