Internal documentation lacks dependency management policy

[jrw972]

Problem

The internal (developer) documentation lacks the policy used for managing the dependencies of OpenDDS.

Solution

Add it.

[jrw972]

What about vcpkg?

[iguessthislldo]

This makes it sound like we're not using any branch of ACE/TAO in PR CI at all. With that, I'm concerned about having newly merged features in ACE/TAO and able to test that those are working correctly with an OpenDDS PR CI that's trying to use them.

[jrw972]

This makes it sound like we're not using any branch of ACE/TAO in PR CI at all. With that, I'm concerned about having newly merged features in ACE/TAO and able to test that those are working correctly with an OpenDDS PR CI that's trying to use them.

If a PR requires an unreleased feature of ACE/TAO, then the PR author is free to change the ACE/TAO versions from release to the branches for the purpose of CI. However, I would push back against merging such a PR until the feature makes it into a released version of ACE/TAO at which point the ACE/TAO versions could be updated to a release version.

[iguessthislldo]

I would suggest something like an environment variable in the workflows to make it easier to switch the PRs to use git branches and maybe a lint check to make sure we don't accidentally merge that.