[Mike Seese] Build UE plugin with plugin dependencies

[hach-que]

I have a plugin that has other plugin dependencies. I'd like to use uet build for a specific plugin and configure uet to know where to look for non-engine plugin dependencies (perhaps an array of directories to recursively look for uplugins). I do colocate these plugins (I have a monorepo with 2 of my plugins and 4 third party plugins all under a single ancestor directory), so an alternative solution would to build each of the plugins (recursively) for a specific folder (resolving the dependency tree first)