fix(scim): Add scimType and status to SCIM error responses

[Asynchronite]

Summary

Sentry's SCIM error responses were missing two members that RFC 7644
§3.12 requires:

• status — the HTTP status code, as a string, on every SCIM error body.
• scimType — "uniqueness" for unique-attribute collisions.

Why this matters

When an IdP provisions a user whose email already exists in the org, Sentry
correctly returns 409, but the body omits scimType: "uniqueness". Spec-
compliant IdPs (e.g. Microsoft Entra) rely on that value to recognize "this user
already exists" and fall back from POST to PATCH/PUT against the existing
record. Without it, the operation hard-fails. This is the normal initial-sync
path: any org that had SAML2 SSO before enabling SCIM already has members (via
JIT or manual invite), so the IdP's first pass POSTs users that already exist.

Before

{
  "schemas": ["urn:ietf:params:scim:api:messages:2.0:Error"],
  "detail": "User already exists in the database."
}

After

{
  "schemas": ["urn:ietf:params:scim:api:messages:2.0:Error"],
  "scimType": "uniqueness",
  "status": "409",
  "detail": "User already exists in the database."
}

Changes

• Add status (string) in the shared SCIMApiError builder and the static SCIM
  error constants, so all SCIM error responses are compliant.
• Set scimType: "uniqueness" on both unique-attribute 409 paths: duplicate
  user (member create) and duplicate team/group slug (team create).
• The team-create duplicate path previously returned a non-SCIM body (no schema
  URN); it now raises SCIMApiError for a proper SCIM error envelope.

Additive only: the 409 status code, detail text, and schema URN are
unchanged, so existing clients are unaffected.

Tests

• Updated the SCIM member/team endpoint tests to assert the new scimType /
  status fields on the uniqueness cases.
• Added a regression test confirming non-uniqueness SCIM errors still return
  valid bodies that include a string status (and no spurious scimType).

Closing Issues

Closes #117860.

Legal Boilerplate

Look, I get it. The entity doing business as "Sentry" was incorporated in the State of Delaware in 2015 as Functional Software, Inc. and is gonna need some rights from me in order to utilize my contributions in this here PR. So here's the deal: I retain all rights, title and interest in and to my contributions, and by keeping this boilerplate intact I confirm that Sentry can use, modify, copy, and redistribute my contributions, under Sentry's choice of terms.

[Asynchronite]

All tests pass! If someone would be so kind as to add the Trigger: getsentry tests label I would appreciate it a great ton!