Various enhancements

[robertkiel]

Re hoprnet/hoprnet#5951

Invalid links

Setting the mainService property in dappnode_package.json assigns the main DNS entry, in this case hopr.public.dappnode to the defined service, which in our case is node.

This PR changes all URLs directing to node.hopr.public.dappnode to hopr.public.dappnode, including the prometheus target

Yarn removal

The dappnodesdk uses npm and npx (npx @dappnode/dappnodesdk build) and refuses to work with yarn for unknown reasons. This PR removes all yarn-related settings and files.

Enhance development documentation

This PR adds helpful information on how to build and debug DAppnode packages. See DEVELOPMENT.md

Out of scope

• Automatic import of prebuild Grafana dashboards as it appears to be broken at the moment.
• Automatic retrieval of IPFS hash when releasing package
• Automatic patching of Grafana dashboard (take the one used in Kubernetes and adapt it for DAppnode) by replacing incorrect entries with jq