add AWSBraketProvider

[salmma]

To support the analysis of compiled circuits BEFORE executing (as it is done in AWS Braket SDK directly), add the AWSBraketProvider Python package to the qiskit-service.

Therefore

• add a counterpart to the ibmq_handler for AWS, see here
• extend routes.py by checking if the received QPU in the request is an IBMQ backend or a supported one of AWS, transpile it and analyze it as given
• extend the tasks.py to support executing circuits via AWS
• extend the README file to mention the new features

[salmma]

To define which provider has to be considered. A "provider" attribute has to be added into the request body of the /transpile and /execute endpoints. Like here.
Thereby, set IBMQ as default value to avoid breaks in non-updated components.

[DominikVoigt]

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