prompt modal to update metadata

[5-mark]

User Story

As loggedin user I want to receive a modal prompt when there is metadata to update so I can be sure I receive the latest network API setup in my wallet.

Acceptance Criteria

1. when the wallet connects to the network it will be checked if there is new metadata available
2. if there is new metadata available a modal shows up with the message "update metadata for best user experience"
3. a call to action is provided which triggers a wallet popup to sign the transaction
4. after signing the metadata are updated

Additional Information

• visit eg. https://apps.karura.network/ to reproduce (only available if you didnt update metadata of karura lately)
• metadata can be found in the polkadot.js wallet here: https://polkadot.js.org/apps/#/settings/metadata (Settings--> Metadata)

How to test

1. update chain so that new metadata are available
2. go to beta and connect wallet
3. see modal appearing with text and CTA
4. click CTA and sign
5. have latest metadata

[5-mark]

@mikeplanzer please come up with a generic modal solution which we can also use for other use cases.