OSBuild - add support for generic S3 services

jobimpl-osbuild
---------------
Add GenericS3Creds to struct
Add method to create AWS with Endpoint for Generic S3 (with its own credentials file)
Move uploading to S3 and result handling to a separate method (along with the special VMDK handling)
adjust the AWS S3 case to the new method
Implement a new case for uploading to a generic S3 service

awscloud
--------
Add wrapper methods for endpoint support
Set the endpoint to the AWS session
Set s3ForcePathStyle to true if endpoint was set

Target
------
Define a new target type for the GenericS3Target and Options
Handle unmarshaling of the target options and result for the Generic S3

Weldr
-----
Add support for only uploading to AWS S3
Define new structures for AWS S3 and Generic S3 (based on AWS S3)
Handle unmarshaling of the providers settings' upload settings

main
----
Add a section in the main config for the Generic S3 service for credentials
If provided pass the credentials file name to the osbuild job implementation

Upload Utility
--------------
Add upload-generic-s3 utility

Makefile
------
Do not fail if the bin directory already exists

Tests
-----
Add test cases for both AWS and a generic S3 server
Add a generic s3_test.sh file for both test cases and add it to the tests RPM spec
Adjust the libvirt test case script to support already created images
GitLabCI - Extend the libvirt test case to include the two new tests

cmd/osbuild-upload-generic-s3/main.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+
+	"github.com/aws/aws-sdk-go/aws"
+
+	"github.com/osbuild/osbuild-composer/internal/cloud/awscloud"
+)
+
+func main() {
+	var accessKeyID string
+	var secretAccessKey string
+	var sessionToken string
+	var region string
+	var endpoint string
+	var bucketName string
+	var keyName string
+	var filename string
+	flag.StringVar(&accessKeyID, "access-key-id", "", "access key ID")
+	flag.StringVar(&secretAccessKey, "secret-access-key", "", "secret access key")
+	flag.StringVar(&sessionToken, "session-token", "", "session token")
+	flag.StringVar(&region, "region", "", "target region")
+	flag.StringVar(&endpoint, "endpoint", "", "target endpoint")
+	flag.StringVar(&bucketName, "bucket", "", "target S3 bucket name")
+	flag.StringVar(&keyName, "key", "", "target S3 key name")
+	flag.StringVar(&filename, "image", "", "image file to upload")
+	flag.Parse()
+
+	a, err := awscloud.NewForEndpoint(endpoint, region, accessKeyID, secretAccessKey, sessionToken)
+	if err != nil {
+		println(err.Error())
+		return
+	}
+
+	uploadOutput, err := a.Upload(filename, bucketName, keyName)
+	if err != nil {
+		println(err.Error())
+		return
+	}
+
+	fmt.Printf("file uploaded to %s\n", aws.StringValue(&uploadOutput.Location))
+}