Render strings in bedrock test cassettes for readability

[anuraaga]

Description

Previously API recordings for AWS SDK Bedrock instrumentation tests were formatted as binary making them unreadable in things like code review. This formats them to

• Pretty-print raw JSON in request and response where possible (bedrock streaming responses are actually a binary protocol and remain as binary)
• Print request headers as strings
• Use multiline strings for long ones

/cc @xrmx @codefromthecrypt

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Unit tests

Does This PR Require a Core Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[codefromthecrypt]

This is much better as at least the request side is completely readable now, as is the response side non-streaming. Streaming responses use a binary format, so while the body cannot be improved, the headers are.

Good work!

[xrmx]

Looks great, thanks!