Testing with Mock AwsDevice

[ryanhill1]

Instead of testing against the Amazon Braket devices, we want switch relevant tests to construct Mock AwsDevice classes so that contributors don't need AWS credentials to run unit tests.

Creating mock AWS devices for testing can be modeled after the following examples:

• https://github.com/qiskit-community/qiskit-braket-provider/blob/main/tests/providers/test_braket_backend.py
• https://github.com/aws/amazon-braket-sdk-python/blob/main/test/unit_tests/braket/aws/test_aws_device.py
• https://github.com/CQCL/pytket-braket/blob/develop/tests/backend_test.py

Mock device updates will effect the following qBraid test modules:

• https://github.com/qBraid/qBraid/blob/main/tests/runtime/test_braket_device.py
• https://github.com/qBraid/qBraid/blob/main/tests/runtime/test_braket_provider.py