Add hydra as tool to developer platform

[ch1bo]

Why

Hydra requires adoption of applications to improve the scalability of Cardano.

The hydra-node can be used to create layer 2 networks, which can serve as flexible ad-hoc transaction processing systems or persistent parts of a decentralized application.

What

The developer platform on cardano.org has a nice area for builder tools: https://developers.cardano.org/tools/

We want to make sure Hydra is present there, ideally as one of the favorite tools

How

Follow the contribution guidelines of the platform and create a pull request to add Hydra https://github.com/cardano-foundation/developer-portal/edit/staging/src/data/builder-tools.js

Also propose to introduce a "Hydra" domain label to tag this and future tools which support Hydra (e.g. Kupo will be made compatible with Hydra).

[v0d1ch]

Upstream PR cardano-foundation/developer-portal#1088

[ch1bo]