Feat req.: Add ability to download data embeded in QR codes

[nuke-web3]

The portal's various QR codes don't include any way to get the data that is present in the QR codes. The metadata portal should provide that as a raw download link too, not just the QR.

Related to #28 but also just for convenience, this option would be a user friendly way to get that data for this portal as well as https://github.com/novasamatech/metadata-portal fork of this repo, where various parachains are listed.

[prybalko]

Could you elaborate on what the use case is for this feature?

[nuke-web3]

https://matrix.to/#/!DdfYhHuqjPrESXfCDj:parity.io/$tCMRJ-VP9T3DkVwoowaTdz5LRS8Puh_YN5oQ2m6gfsc?via=parity.io&via=web3.foundation

I want to validate and use the metadata for things outside the Vault. As this data is already here, but there is no way to get it on the portal without scanning it.

[prybalko]

subxt might be the better tool for this.

It's more flexible and supports multiple formats: json, hex or bytes.

Example usage:

subxt metadata --url="https://westend-rpc.polkadot.io:443" -f bytes

Moreover, Metadata Portal might be deprecated once paritytech/polkadot-sdk#291 is merged.