[13.0] ir_attachment_s3: error in case when bucket is not created in AWS

[trojikman]

Steps to reproduce:

1. Install and configure module as described in docs
2. Don't create bucket in AWS
3. You'll get an error like "Access denied"

How it should work:
If bucket name passed in s3.bucket doesn't exist in AWS S3 then it must be created.

Where to fix:

misc-addons/ir_attachment_s3/models/res_config_settings.py

Lines 45 to 52 in fa47493

	s3 = boto3.resource(
	"s3", aws_access_key_id=access_key_id, aws_secret_access_key=secret_key
	)
	bucket = s3.Bucket(bucket_name)
	if not bucket:
	s3.create_bucket(Bucket=bucket_name)
	bucket = s3.Bucket(bucket_name)
	return bucket

the bucket variable is True even if there is no buckets in S3.

Might help:
https://stackoverflow.com/questions/26871884/how-can-i-easily-determine-if-a-boto-3-s3-bucket-resource-exists

It was mentioned here

[trojikman]

I also thought that it would be nice to do something like a check for the uniqueness of the bucket name in case when bucket haven't created in S3 yet.