[FR] V4 - Add ECB Provider for ECB Yield Curve

[jmaslek]

What's the problem of not having this feature? A clear description of what you are lacking, or why you need this additional feature.

Describe the solution you would like A description of what you think would be the best solution for this. From user inputs, to an output.

Describe alternatives you've considered If there are other alternatives (worth considering) to your solution, list them here.

Additional information Add any other information or screenshots about the feature request here.