Add function to extract anchor data from certificate

[palas]

Changelog

- description: |
    - Add function to extract anchor data from a certificate
  type:
  - feature

Context

This PR is part of addressing this review comment. It moves the extracting of anchor data into cardano-api together with the rest of code that inspects certificates for easier maintenance.

Related PRs

• [cardano-cli] Add anchor hash checks to transaction build cardano-cli#951
• [cardano-node] Hash check in transaction build tests cardano-node#6023

How to trust this PR

It is quite analogous to filterUnRegDRepCreds, except it does some conversion from PoolMetadata to AnchorData which are analogous types.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[Jimbo4350]

Let's stick with Either please. I don't want a mixture of MonadError and Either.