Add options to ignore `mermaid` diagram

[Airkro]

Some diagram types have their own VS Code Extensions, like Mermaid / PlantUML, but this extension will override all of them, even if it doesn't need to.

[LSP-Dekimo]

In addition the kroki extension also currently errors on rendering mermaid diagrams (that build in mermaid preview renders fine). This is annoying since i use multiple diagram types in the same file, so I can either enable kroki -> breaks mermaid, but others are fine OR disable kroki -> mermaid works, but others are not rendered.