Add new node-type for OpenDSS

[stv0g]

Continuation of #887

TODO:

Add integration test
Add OpenAPI spec
Add Documentation

[stv0g]

@JitpanuM I think, I got most of the build issues fixed. But there is a problem with the example config and the integration test thereof. Could you have a look?

[JitpanuM]

It seem like opendss change the working directory to /home/user/OpenDSS. That is why the integration test couldn't find the config file.

[stv0g]

Ouch, that's annoying. Do you already have an idea how we can fix it?

[JitpanuM]

I think that modifing their source code to set the current working directory back should work.

[stv0g]

Urgh, we get some flaky / broken integration tests now :(

I suspect that something with the timing changed.. Maybe loading the libopendssc.so library or any of the other version updates is causing this :(

We will need to split-up this PR into smaller ones unfortunately :(

[stv0g]

I moved a bunch of unreleated updates to this PR #893

[stv0g]

Okay, the Docker image updates (#893) have been merged into master, and I have rebased this PR onto it.

I also did some cleanup of the Git history. Please reset your local branch before pushing any more changes :) Thanks :)

[stv0g]

Okay, two more fixes:

• For some reason a member variable of an unrelated hook was not properly initialized and caused a test to fail
• For some other reason OpenDSS is seeding the random number generator differently than VILLASnode did in the past. This broke another test.