feature: Customizable inheritance diagram chart direction

[nfelt14]

Is your feature request related to a problem? Please describe.

When I create an inheritance diagram, I have so many parent classes due to Mixins that I can't read it as it is too small. If the direction were to change I would be able to read it.

Describe the solution you'd like

It would be nice if the configuration option for the inheritance diagram would allow the user to pass in a string indicating the direction of the mermaid chart. (e.g. LR, RL, TB, etc.)

Describe alternatives you've considered

The only alternative right now is overriding with templates, but that leads to a lot of duplicate code for no reason.

Additional context

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