ref(boto3): Own one logical botocore client-call lifecycle

[pabloDeputter]

Problem

• spans are currently created in request-created. Botocore may emit this during retries; it's also too late to cover any failures during operation lookup, parameter construction, serialization, or other work before an HTTP request exists.

Proposed Solution

• patch BaseClient._make_api_call as OTel does; one logical client span should cover all retries until response, error, or cancellation.
• wrapper is the only owner of the aws client span's start and completion.
• _AwsCallContext can be used to contain generic data such botocore client, service name, operation name, region, endpoint URL, etc

Sources

• https://opentelemetry.io/docs/specs/semconv/rpc/rpc-spans/#rpc-client-span
• https://github.com/boto/botocore/blob/develop/botocore/client.py
• https://github.com/open-telemetry/opentelemetry-python-contrib/blob/main/instrumentation/opentelemetry-instrumentation-botocore/src/opentelemetry/instrumentation/botocore/init.py

[linear-code]

PY-2774