Provide metadata when signing delegation

[jeffsmale90]

Description

When the GatorPermissionsSnap submits the delegation for signing via eth_signTypedData_v4, it must include metadata - the justification, and origin of the request, as part of the eip-712 payload.

Related issues

MetaMask/core#6619
MetaMask/core#6656
MetaMask/metamask-extension#36054

Manual testing steps

1. Ensure you have a build of Extension that
   a. Has the above PRs integrated
   b. Has the GATOR_PERMISSIONS_ENABLED environment variable set to true
2. Go through the normal process of requesting a permission
3. After clicking "Grant" on the permission picker screen, note the justification and origin that are show are the originating dapp (probably localhost:8000 if using the site from the snap monorepo, and "This is a very important request for streaming allowance for some very important thing" if you don't change it)

Screenshots/Recordings

Before

Error would be shown, because no metadata is included in the request.

After

Pre-merge author checklist

• I've followed MetaMask 7715 Permissions Snaps Contributor Docs and MetaMask 7715 Permissions Snaps Coding Standards.
• I've completed the PR template to the best of my ability
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

[mj-kiwi]

Looks good to me! Just a minor suggestion — have you considered extracting a metadata type:

export type DelegationMetadata = {
  origin: string;
  justification: string;
};

[jeffsmale90]

Looks good to me! Just a minor suggestion — have you considered extracting a metadata type:

Yeah, that might not be a bad idea - I left the properties of SignDelegationOptions flat to not let the shape of the signTypedData parameters leak out into the interface. We could look to tidy up in the future though.