AWS SNS integration could perform some input validation

[glynj-bsquare]

• The issue is present in the latest release.
• I have searched the issues of this repository and believe that this is not a duplicate.

What happened?

I attempted to configure AWS SNS integration, but no messages were posted into the queue due to additional invisible characters appended to the aws_access_key_id.

What did you expect?

A warning that the key did not match the expected format (i.e. had space or CR/LF at the end), or for them to be silently removed.

Steps to reproduce this issue

Steps:

1. I pasted the aws_access_key_id into the box on the configuration screen. It appended a non-visible character, possibly a space or CR/LF. It would have been nice if the screen automatically removed these, or warned that they were there.
2. After removing the invisible character, messages started to flow into AWS SNS. It took some time before this issue was detected, so this bug is raised to assist others from making the same mistake.

Could you share your log output?

No logs or error messages found on device relevant to application integrations.

Your Environment

Component	Version
Application Server
Network Server
Gateway Bridge
Chirpstack API
Geolocation
Concentratord
OpenWRt release	ChirpStack Gateway OS 4.3.2 Full / LuCI openwrt-23.05 branch git-23.355.78874-80140aa