Fleet: Observer-class users can view team enroll secrets and credential-bearing configuration via target search endpoint

Fleet is an open-source device management platform built on osquery. In versions prior to 4.87.0, the target search endpoint (POST /api/latest/fleet/targets) returned unmasked team enroll secrets and full team configuration, including credential-bearing agent options, to low-privilege observer-class users. Other team-facing endpoints mask these fields for observers, but the target search endpoint did not apply the same sanitization, so an authenticated user with the Observer, Observer+, or Technician role, whether global or team-scoped, could retrieve the secrets and agent options by performing a target search against an observer-runnable query. With a leaked team enroll secret an attacker could enroll unauthorized hosts into the affected team, and if the team's agent options contained credentials such as AWS secret access keys or proxy passwords, those values were disclosed as well. This issue is fixed in version 4.87.0.