chore(maintenance): add powertools to user-agent in SDK clients

[am29d]

Description of your changes

In this PR we introduce our custom middleware that can be added to any middleware stack of AWS SDK v3 clients. We decided to use middleware instead of customUserAgent options, because we might get SDK client from the user. Because config field of the client is readonly, we can't add change it, after the client has been initialised.

Any feature using an SDK client can call like this:

const ddbClient = new DynamoDBClient(options);

addUserAgentMiddleware(ddbClient, 'my-feature);

this will modify the user-agent field by appending PT/my-feature/1.10.0 PTEnv/NA at the end of the value.

I was about to add the new functionality to idempotency, but we will do it in a separate PR. Meanwhile, I have removed the singleton for the client in the DynamoDBPersistenceLayer.ts, similar how we use it parameters utility.

Related issues, RFCs

Issue number: closes #1533

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my change is effective and works
• The PR title follows the conventional commit semantics

Breaking change checklist

Is it a breaking change?: NO

• I have documented the migration process
• I have added, implemented necessary warnings (if it can live side by side)

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[am29d]

• Fixed tests
• added try/catch so we don't block user code if adding user agent fails
• added parametrised tests for each client we use in our utilities

[dreamorosi]

Thanks for working on this.

I have run the integration tests on this branch and they are passing.

[dreamorosi]

Very clean, I like it