[FEATURE] Support custom MiniMap Node components

[thedanchez]

In React Flow, the MiniMap component supports the ability to pass in a custom component that can be used to render custom visual representations of nodes on the MiniMap. This issue is to track adding that capability to Solid Flow:

https://github.com/thedanchez/xyflow/blob/a75087e8d3a6ea0731f5bd2331027dc89edce85c/packages/react/src/additional-components/MiniMap/MiniMap.tsx