Return false from checkIfCacheExists when error is 403

[leighpascoe]

Fixes issue #433

When GetHeadObject command is returned if you don't have s3:ListBucket permissions, then you will receive a 403 error. This case would still indicate that the bucket object exists.

See: https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/s3/command/HeadObjectCommand/

General purpose bucket permissions - To use HEAD, you must have the s3:GetObject permission. You need the relevant read object (or version) permission for this operation. For more information, see Actions, resources, and condition keys for Amazon S3 in the Amazon S3 User Guide.

If the object you request doesn't exist, the error that Amazon S3 returns depends on whether you also have the s3:ListBucket permission.

If you have the s3:ListBucket permission on the bucket, Amazon S3 returns an HTTP status code 404 Not Found error.

If you don’t have the s3:ListBucket permission, Amazon S3 returns an HTTP status code 403 Forbidden error

The same solution exists in the nx-remotecache-s3 project

https://github.com/robinpellegrims/pellegrims/blob/master/libs/nx-remotecache-s3/src/lib/setup-s3-task-runner.ts#L44-L45