Color and default vis

• Add has_best_match function which add an attribute to every node for which we cannot find an implementation to use (for example because input/output datatype does not match) and colorize these nodes in red. This attribute is named fail_best_match and contains the description of the current node specs and the specs for which Aidge has a registered impelmentation.
• Add support of special attribute on nodes to apply node style.
  • model_explorer:bg_color: Changes the background color of the node. The value must be a string representing a valid color in hexadecimal format (e.g., "#ff0800" for red). The string should follow the standard 6-digit RGB hex code format, beginning with a #.
  • model_explorer:border_color: Changes the border color of the node. The value must be a string representing a valid color in hexadecimal format (e.g., "#ff0800" for red). The string should follow the standard 6-digit RGB hex code format, beginning with a #.
  • model_explorer:h_border_color: Changes the border color on hover of the node. The value must be a string representing a valid color in hexadecimal format (e.g., "#ff0800" for red). The string should follow the standard 6-digit RGB hex code format, beginning with a #.