Add Wrapcast API methods for signer requests

[michaelhly]

Is your feature request related to a problem? Please describe. Add wrapper methods for new Warpcast APIs supporting the signer request flow: https://warpcast.notion.site/Warpcast-v2-API-Documentation-c19a9494383a4ce0bd28db6d44d99ea8#13cb11cba1114002adc928c5fa679364

Describe the solution you'd like n/a

Describe alternatives you've considered n/a

Additional context https://warpcast.notion.site/Warpcast-API-Docs-Signer-Requests-Public-e02ef71883374d2ca8d27239a8cc35d5

[gsgalloway]

On it

[github-actions[bot]]

:tada: This issue has been resolved in version 5.6.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: