Kvssink no credentials found error message

[sirknightj]

Issue #, if available:

• Failure to connect to Kinesis: Failed to init kvs producer. Error: Unable to create Rotating Credential provider. #976

Background:
When you run kvssink, and it was not able to find any credentials, it fails with this code:

Failed to init kvs producer. Error: Unable to create Rotating Credential provider. Error status: 0x15000022
Which is:

• STATUS_FILE_CREDENTIAL_PROVIDER_OPEN_FILE_FAILED

It will fallback to the file credentials and fail: https://docs.aws.amazon.com/kinesisvideostreams/latest/dg/examples-gstreamer-plugin-parameters.html#credentials-to-kvssink

Logic should be revised to have a better error message.

Description of changes:

• Change to have a better error message.
• In kvssink, check if the credentials file exists. If so, try the file credentials provider. Otherwise, print a proper error.

Testing with gst-parse-launch-1.0:

[INFO ] [05-02-2025 23:15:31:074.995 UTC] Logger config being used: ../kvs_log_configuration
ERROR: from element /GstPipeline:pipeline0/GstKvsSink:kvssink0: Could not initialize supporting library.
Additional debug info:
/Users/me/Downloads/amazon-kinesis-video-streams-producer-sdk-cpp/src/gstreamer/gstkvssink.cpp(1642): gst_kvs_sink_change_state (): /GstPipeline:pipeline0/GstKvsSink:kvssink0:
Failed to init kvs producer. Error: Could not find any AWS credentials!
ERROR: pipeline doesn't want to preroll.
Failed to set pipeline to PAUSED.
Setting pipeline to NULL ...
Freeing pipeline ...

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.