Adapt to directed codegen

[ganeshnj]

Describe the bug

When Swift codegen was initially done, devs created a lot of boiler plate code for smithy. Based on the experience of newer SDKs, Smithy Introduced DirectedCodegen which reduces boilerplate and make codegen consistent across SDKs.

Expected Behavior

Use https://smithy.io/javadoc/1.21.0/index.html?software/amazon/smithy/codegen/core/directed/DirectedCodegen.html

Current Behavior

Using hand written boilerplate.

Reproduction Steps

None.

Possible Solution

No response

Additional Information/Context

No response

AWS SWIFT SDK version used

NA

Compiler and Version used

NA

Operating System and version

NA