Add multip-port-sg module

[qrilka]

---

name: Multip-port security group module

Please include the following in your PR:

Please also note that these are not hard requirements, but merely serve to define
what maintainers are looking for in PR's. Including these will more likely lead
to your PR being reviewed and accepted.

• Update the changelog
• Make sure that modules and files are documented. This can be done inside the module and files.
• Make sure that new modules directories contain a basic README.md file.
• Make sure that the module is added to tests/main.tf
• Make sure that the linting passes on CI.
• Make sure that there is an up to date example for your code:
  - For new modules this would entail example code for how to use the module or some explanation in the module readme.
  - For new examples please provide a README explaining how to run the example. It's also ideal to provide a basic makefile to use the example as well.
• Make sure that there is a manual CI trigger that can test the deployment.

[qrilka]

The main motivation for this module is the fact that TF 0.12 doesn't allow for_each to be used with modules (though the argument is already reserved for future versions). Because of that single-port-sg can't be used with a list of ports to open and this module allows this to be done.

[ketzacoatl]

Minor updates:

• add example to the doc
• update tests/main.tf to include this module with empty params

[ketzacoatl]

Please add an example of how you intend the module to be used.

[ketzacoatl]

Separate the above into a variables.tf

[ketzacoatl]

This looks great!