Add S3 bucket name suffix and tagging options

[thilinapiy]

Adding following options to stackit cli.

* `--stackit-s3-suffix "random"`
If the s3 bucket stackit creates requires a unique S3 bucket name.

* `--stackit-tags "key=val,key2=val2"`
If the s3 bucket stackit creates requires tags, you can add them with this flag.