C4 container and component external artifacts

[stawirej]

For well-designed systems current set of C4-PalntUML artifacts are sufficient.
When working with monoliths a.k.a "Big Ball of Mud" we have an issue with correctly distinguish which container and/or component
is under the team responsibility. Some containers/components are relevant from use-case perspective. Therefore, they should be
present on a diagram to give full use-case picture. In the same time they should be marked as "external"
as team is not responsible nor develop them. This can be easily achieved by introducing "external" container/component artifacts in C4-PlantUML.

[ncasaux]

Nice! External container makes sense when for example, in an application, you use a "database as a service" but you don't really own the database itself.

[kamil-duda]

@RicardoNiepel @adrianvlupu Could we merge these elements? 😃

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[adrianvlupu]

I already included this in #84, I made the merge from @stawirej repo

Edit:
Ok, noticed he doesn't show up in my commit history, maybe it's because I rewritten most of the files, if you want the commit as it is, commit it as it is and I'll fix it when merging #84 if it comes to that

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.