Update AWS deployment

[ekansa]

brief description of changes

This updates AWS deployment and provides more direction on deployment options, including architecture choices to distribute Arches and Arches dependencies across multiple EC2 instances, the RDS service, etc.

issues addressed

These directions have been tagged as out-of-date for some time.

further comments

Thanks to @aarongundel for his AWS walk through. Thanks also to his architecture diagrams. I probably garbled or omitted some key points, but I'd be in much worse shape without his help.

The updated instructions are temporarily deployed here: https://arches.readthedocs.io/en/aws_7_4/deployment/migrating-a-local-app-to-aws-ec2/

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This box must be checked

• [x] the PR branch was originally made from the base branch

This box should be checked

• [x] after these changes the docs build locally without error

This box should only be checked you intend to follow through on it (we can do it on our end too)

• [ ] I will cherry-pick all commits in this PR into other branches that should have them after this PR is merged

[ekansa]

Thanks @mradamcox ! We'll probably have lots more helpful details to add in the future, but for now, I'll merge this since it could be helpful.