Support to upload report to custom S3 (minio)

[Vatson112]

Description

It will be nice to have oportunity to use custom s3 provider like Minio.

Minio is AWS S3 compatible, so we can use ordinary aws cli with it. For example:

aws --endpoint-url https://play.min.io:9000 s3 ls

Therefore I think it's possible to implement this without completely rewriting the current implementation.

Unfortunatly, I dont have any expirience with AWS and AWS-SDK to realise it by myself.

[MaineK00n]

This part of the implementation should work if you follow the minio documentation below.

vuls/reporter/s3.go

Lines 38 to 45 in 7044929

	config := &aws.Config{
	Region: aws.String(w.Region),
	Credentials: credentials.NewChainCredentials([]credentials.Provider{
	&credentials.EnvProvider{},
	&credentials.SharedCredentialsProvider{Filename: "", Profile: w.Profile},
	&ec2rolecreds.EC2RoleProvider{Client: ec2metadata.New(ses)},
	}),
	}

https://github.com/krishnasrinivas/cookbook/blob/master/docs/aws-sdk-for-go-with-minio.md