Add Application Signals runtime metrics

[bjrara]

Feature request

Add runtime metrics collection into Application Signals. Runtime metrics will be enabled by default if OTEL_AWS_APPLICATION_SIGNALS_ENABLED is true, and can be disabled separately by setting OTEL_AWS_APPLICATION_SIGNALS_RUNTIME_ENABLED to false.

Description of changes:

1. Add ScopeBasedPeriodicExportingMetricReader to copy metrics from opentelemetry.instrumentation.system_metrics instrumentation scope to Application Signals exporter.
2. Set aws.local.service into resource attributes.
3. Add views to workaround Multiple system metrics return negative values when using DELTA temporality. open-telemetry/opentelemetry-python-contrib#2861.
4. Add contract testing for runtime metrics.

Result example

{
  "resource_metrics": [
    {
      "resource": {
        "attributes": {
          "telemetry.sdk.language": "python",
          "telemetry.sdk.name": "opentelemetry",
          "telemetry.sdk.version": "1.25.0",
          "service.name": "unknown_service",
          "cloud.provider": "aws",
          "cloud.platform": "aws_ec2",
          "cloud.account.id": "633750930120",
          "cloud.region": "us-east-1",
          "cloud.availability_zone": "us-east-1a",
          "host.id": "i-03ff80a878a803e0e",
          "host.type": "t2.medium",
          "host.name": "ip-172-31-25-215.ec2.internal",
          "telemetry.auto.version": "0.3.0.dev0-aws",
          "aws.local.service": "UnknownService"
        },
        "schema_url": ""
      },
      "scope_metrics": [
        {
          "scope": {
            "name": "opentelemetry.instrumentation.system_metrics",
            "version": "0.46b0",
            "schema_url": "https://opentelemetry.io/schemas/1.11.0"
          },
          "metrics": [
            {
              "name": "process.runtime.cpython.memory",
              "description": "Runtime cpython memory",
              "unit": "bytes",
              "data": {
                "data_points": [
                  {
                    "attributes": {
                      "type": "rss"
                    },
                    "start_time_unix_nano": 1724953385390606423,
                    "time_unix_nano": 1724953385391126083,
                    "value": 75747328
                  },
                  {
                    "attributes": {
                      "type": "vms"
                    },
                    "start_time_unix_nano": 1724953385390606423,
                    "time_unix_nano": 1724953385391126083,
                    "value": 546709504
                  }
                ],
                "aggregation_temporality": 2,
                "is_monotonic": false
              }
            }
          ]
        }
      ]
    }
  ]
}

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.