feat: Add new sub-module for AWS flow log

[bryantbiggs]

Description

• Add new sub-module for AWS flow log

Motivation and Context

• To support more scenarios
  • Multiple flow logs per VPC
  • Flow logs outside of this module (feat: Add Flow Log Support terraform-aws-transit-gateway#145)
• This a precursory change that is valid in this modules current form. At the next breaking change the embedded flow log implementation will be removed and users migrated to the sub-module instead. Adding this now reduces the size/scope of that later PR

Breaking Changes

• No, all changes are self-contained to this new sub-module only. The example as well as example outputs have been removed to start dissuading users from using the current implementation and look to use this sub-module instead. However, current functionality remains intact and untouched

How Has This Been Tested?

• I have updated at least one of the examples/* to demonstrate and validate my change(s)
• I have tested and validated these changes using one or more of the provided examples/* projects
• I have executed pre-commit run -a on my pull request

[bryantbiggs]

these versions are different from the rest of the repository but that is intention. It does not affect anything else in the module, but we want to start off on these versions

[antonbabenko]

Minor comments

[antonbabenko]

This PR is included in version 6.3.0 🎉

[github-actions]

I'm going to lock this pull request because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues. If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.