Display more meaningful information in DID Replicas view

[maany]

🐞 Description
When viewing a DID page for a dataset and navigating to the Replicas tab, the current table displays a list of file-level replicas—specifically showing the RSE and State for each file in the dataset:

💡 Motivation This view is not very helpful for users looking to understand the replica status of the dataset itself. File-level details are already available in the Content Replicas view. Users expect this Replicas tab to provide a dataset-level overview, not a breakdown of individual files.

✅ Proposed Change
Update the Replicas tab for datasets to display replica information at the dataset level, using the following fields:

RSE — the storage endpoint.

Replication Progress Bar — calculated as available_length / length, representing how much of the dataset is available at each RSE.

🔗 Source of Data
The dataset-level replica information is already available via the core Rucio logic:

Core logic (returns length and available_length):
https://github.com/rucio/rucio/blob/6d473205cb846c96fbf08b1e9edea7027cc9baa1/lib/rucio/core/replica.py#L3415

Exposed via the following REST API endpoint:
GET /replicas/{scope_name}/datasets