Move taquito-metadata-explorer into the Taquito website

[jevonearth]

Is your feature request related to a problem and use case? Please describe.

The metadata-explorer is for exploring contract and token metadata and by extension, for testing that Taquito's TZIP-12/16 support.

Describe the solution you'd like

Move the https://github.com/claudebarde/taquito-metadata-explorer into the Taquito git repository.

On PR's, when the Taquito website gets deployed to a preview build, the metadata-explorer should also be built and published to https://PREVIEW_URL/metadata-explorer

Describe alternatives you've considered

Trigger auto-updates to the current downstream https://github.com/claudebarde/taquito-metadata-explorer and have that update to the latest build. Rejecting this idea as it is too complex.

Acceptance criteria

When a PR is created, CI creates a website preview such as https://9f5eb399--tezostaquito.netlify.app. The following criteria will use this URL as an example.

• Project should be located under apps/metadata-explorer
• Project must be marked as private so that it does not publish to NPM
• The metadata-explorer must be built against the local taquito code base (not npm packages) so that its functions rely on the taquito code in the same branch.
• The metadata-explorer must be published to https://9f5eb399--tezostaquito.netlify.app/metadata-explorer.
• When the PR is merged to master, the website will build, and the test dapp will publish to https://tezostaquito.io/metadata-explorer.

[jevonearth]

Very similar work to #663

[michaelkernaghan]

meta data explorer has been dropped in favour of indexers such as tzkt and breaking bad which handed the eta data indexing.