GET /me/tokens: Add crate_scopes and endpoint_scopes fields

[Turbo87]

These fields will be null if the token was created without any crate or endpoint scopes, or they will be arrays of the chosen scopes.

Note that these fields are considered experimental and we don't give any stability guarantees for now!

Example:

{
  // ...
  "crate_scopes": ["serde", "serde-*"]
  "endpoint_scopes": ["publish-new", "publish-update"],
}

Related:

• Tracking Issue: Token Scopes #5443
• crates.io token scopes rfcs#2947
• Add crate_scopes and endpoint_scopes fields to the PUT /me/tokens API endpoint #5973