Idea: Add model-factory as a git submodule or subtree of opendrr-api

[anthonyfok]

OpenDRR/opendrr-api and OpenDRR/model-factory are inextricably related, and their versions often have to match for the stack build to run successfully and produce correct results.

While we have started to match the release tag in add_data.sh, it may be a good idea to have OpenDRR/model-factory as a git "submodule" or "subtree" of OpenDRR/opendrr-api to make that versioned relationship explicit. This will also facilitate testing on master and topic branches without having to create a temporary test release tag.

It may also be a good idea to include most or all other dependent repos: OpenDRR/boundaries, OpenDRR/CanadaSRM, OpenDRR/earthquake-scenarios, OpenDRR/model-inputs, OpenDRR/openquake-inputs as submodules of OpenDRR/opendrr-api too.

Thanks to HabitSeven for the inspiration where the WordPress theme is included as a submodule, which is also a common practice for Hugo websites. Also, Hugo (https://github.com/gohugoio/hugo) started with including hugoDocs (<https://github.com/gohugoio/hugoDocs) as a submodule for hugoDocs, though eventually switched to subtree.

[jvanulde]

Interesting idea @anthonyfok. Perhaps a demo and/explanation on how it might work would be helpful at our next review meeting.