refactor: Move methods in pkg/clients/ into invidual util packages

[MisterMX]

Description of your changes

This moves the individual pkg/clients/*.go files into their own pkg/utils/ packages to provide better modularization. It also makes imports a bit cleaner as the pkg/clients was imported in the code with many different names (awsclients, awsclient, clients, aws etc.).

There are no functional changes to the code. Only the imports have changed. In a very small amount of places the pointer function has been replaced with the respective one from k8s.io/utils/ptr.

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

n.a.

[chlunde]

I think we should ensure that the replaced functions have identical behaviour, it will be very hard to test if any of these changes have negative side effects?

        controller_test.go:239: r: -want, +got:
              &v1beta1.Topic{
              	TypeMeta:   {},
              	ObjectMeta: {Annotations: {"crossplane.io/external-name": "arn:aws:sns:ap-south-1:862356124505:some-topic"}},
              	Spec: v1beta1.TopicSpec{
              		ResourceSpec: {},
              		ForProvider: v1beta1.TopicParameters{
              			Region:         "",
              			Name:           "some-topic",
              			DisplayName:    &"some-topic-01",
            - 			KMSMasterKeyID: &"",
            + 			KMSMasterKeyID: nil,
            - 			Policy:         &"",
            + 			Policy:         nil,
            - 			DeliveryPolicy: &"",
            + 			DeliveryPolicy: nil,
              			FifoTopic:      nil,
              			Tags:           nil,
              			```

[chlunde]

Enssure we have identical behaviour for empty string vs nil

[MisterMX]

Sorry, I think I messed something up while search-replacing the pointer methods. It should now work without any behavioral changes.