[CloudFront] Add exception when signature generation fails

[DocLM]

See #2608

Description of changes:
On recent RHEL/RockyLinux/Alma 9 the default system security policies disable SHA-1 in OpenSSL.

This cause CloudFrontClient to silently fail signature generation in getSignedUrl and generate an URL with empty signature.
I've added a check for empty signature and an exception with OpenSSL errors to help to identify the issue.
I'd like to add a test but I'm struggling to find a way to dynamically disable the algorithm during unit tests, any suggestion is welcome.

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[yenfryherrerafeliz]

It looks good. Can you just please add a new line in between line 122 and 123?

Thanks!

[DocLM]

@yenfryherrerafeliz refactored and rebased code, ready to go when you are ready!

[yenfryherrerafeliz]

Hi @DocLM, one last thing. Could you please add a generic error message for when $errorMessages is empty. Just to be safe.
For example:

$exceptionMessage = implode("\n",$errorMessages);
if (count($errorMessages) == 0) {
    $exceptionMessage = "An error has occurred when signing the policy";
}

throw new \RuntimeException($exceptionMessage);

Thanks!

[DocLM]

@yenfryherrerafeliz Fallback error message now available!

[stobrien89]

Thanks for the contribution @DocLM!