fix: Invoke stderr stream missing stack trace

[mildaniel]

Which issue(s) does this change fix?

N/A

Why is this change necessary?

After updating sam local commands to use the RIE in version 1.13.1, when a stack trace is streamed from the emulation container it contains carriage return characters that then don't get displayed by the stream writer.

How does it address the issue?

Replaces the carriage return characters with the system's linesep character.

What side effects does this change have?

Will display addition logs when using local invoke commands that contain a stack trace.

Before:

Mounting C:\Users\Administrator\ws\sam-app\.aws-sam\build\HelloWorldFunction as /var/task:ro,delegated, inside runtime container
START RequestId: 06dd2e5e-af4c-47b0-b893-a9979544e244 Version: $LATEST
    "body": son.dumps({y", line 38, in lambda_handler
END RequestId: 06dd2e5e-af4c-47b0-b893-a9979544e244
REPORT RequestId: 06dd2e5e-af4c-47b0-b893-a9979544e244  Init Duration: 0.15 ms  Duration: 155.80 ms     Billed Duration: 156 ms Memory Size: 128 MB     Max Memory Used: 128 MB

After:

Mounting C:\Users\Administrator\ws\sam-app\.aws-sam\build\HelloWorldFunction as /var/task:ro,delegated, inside runtime container
START RequestId: 5ff38d1a-03ed-426a-8a4e-aef0b37bf0de Version: $LATEST
[ERROR] NameError: name 'son' is not defined
Traceback (most recent call last):
  File "/var/task/app.py", line 38, in lambda_handler
    "body": son.dumps({
END RequestId: 5ff38d1a-03ed-426a-8a4e-aef0b37bf0de
REPORT RequestId: 5ff38d1a-03ed-426a-8a4e-aef0b37bf0de  Init Duration: 0.32 ms  Duration: 110.39 ms     Billed Duration: 111 ms Memory Size: 128 MB     Max Memory Used: 128 MB

Mandatory Checklist

PRs will only be reviewed after checklist is complete

• Add input/output type hints to new functions/methods
• Write design document if needed (Do I need to write a design document?)
• Write/update unit tests
• Write/update integration tests
• Write/update functional tests if needed
• make pr passes
• make update-reproducible-reqs if dependencies were changed
• Write documentation

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[mndeveci]

Thanks for fixing this issue! LGTM in general, left a small comment

[sriram-mv]

Overall looks good to me.

Please add a comment in the code which draws attention to this change with something like "Important! DO NOT CHANGE", and an explanation of why. Because the decode, encode can seem like weird behavior.