Draft: Make AwsClientCustomizer Flexible

[MatejNedic]

📢 Type of change

• Bugfix
• New feature
• Enhancement
• Refactoring

📜 Description

💡 Motivation and Context

💚 How did you test it?

📝 Checklist

• I reviewed submitted code
• I added tests to verify changes
• I updated reference documentation to reflect the change
• All tests passing
• No breaking changes

🔮 Next steps

[MatejNedic]

I still need to add more tests and documentation want to first talk about whether are there ways how we can improve and make customization even simpler.

[MatejNedic]

@maciejwalkowiak I was thinking and checking if we can parameterize this somehow through properties. Tbh I am not seeing a clean way to do it, there are just too many options, and some of them you can't even describe in properties.
Maybe we can support just some simple ones as

    private final Duration apiCallAttemptTimeout;
    private final Duration apiCallTimeout;

and apply them in the builder if not null. If not we don't apply to the builder anything besides our applyUserAgent.