Separate unit from integration tests

[omus]

With the switch to using GHA merge queues to deal better with supporting contributions from forks we've discovered a need to run our unit tests and our integration tests separately. By separating these tests we can run the tests which do not require access to the AWS account to be triggered by PR events and reserve the integration tests to be run in the merge queue.

Additionally, this allows for users to run the AWS.jl unit tests locally without any AWS account setup which should allow issues to be caught earlier.

Summary of changes:

• Separate existing tests into unit tests and integration tests. Unit tests now reside under test/unit where as integration tests reside under test/integration. For the most part tests were left as is unless changes were required.
• Rename test/configs directory to test/config.
• Rename test/resources directory to test/resource.
• Removed reference AWS_CONFIG in favor of global_aws_config
• Constant TEST_MINIO was renamed to RUN_MINIO_INTEGRATION_TESTS
• Unit tests attempt to create an environment where an AWS configuration is not present
• Unit tests use AWSConfig(; creds=nothing, region="...") to create a dummy config
• Integration tests are now opt-in instead of opt-out.

Depends on:

• Fix default profile handling when parsing AWS configuration files #727

Fixes #725

[omus]

Looks like the unit tests are polluting the global AWS configuration:

RequestError: Could not resolve host: sts.us-example-1.amazonaws.com while requesting https://sts.us-example-1.amazonaws.com/