Add invalid refresh token error code

[simonfaltum]

Changes

Add an INVALID_REFRESH_TOKEN error code when databricks auth token --output json cannot refresh a cached U2M token. The existing text error and reauthentication guidance remain unchanged.

Why

Clients need a machine-readable way to distinguish an invalid or expired refresh token and trigger a new auth login flow.

Tests

• go test ./cmd/auth ./libs/auth/...
• go test ./acceptance -run TestAccept/cmd/auth/token/force-refresh-invalid-refresh-token -tail -test.v
• ./task fmt
• ./task checks
• ./task lint
• ./task test (the auth changes pass; the unrelated bundle/templates/lakeflow-integrations test fails because the local offline uv cache is missing requests dependencies)

This PR was written by Codex.

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Inputs:

• PR number: 6681
• Commit SHA: eef4736705fb76044e160d8e3bf526d0daf03838

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[github-actions]

Approval status: pending

/cmd/auth/ - needs approval

Files: cmd/auth/token.go, cmd/auth/token_test.go
Suggested: @renaudhartert-db
Also eligible: @mihaimitrea-db, @tanmay-db, @hectorcast-db, @parthban-db, @Divyansh-db, @tejaskochar-db, @chrisst, @rauchy

/libs/auth/ - needs approval

Files: libs/auth/error.go
Suggested: @renaudhartert-db
Also eligible: @mihaimitrea-db, @tanmay-db, @hectorcast-db, @parthban-db, @Divyansh-db, @tejaskochar-db, @chrisst, @rauchy

General files (require maintainer)

Files: .nextchanges/cli/auth-token-error-code.md, acceptance/cmd/auth/token/force-refresh-invalid-refresh-token/output.txt, acceptance/cmd/auth/token/force-refresh-invalid-refresh-token/script
Based on git history:

• @renaudhartert-db -- recent work in cmd/auth/, .nextchanges/cli/, libs/auth/

_{Any maintainer (@andrewnester, @anton-107, @denik, @pietern, @shreyas-goenka, @renaudhartert-db, @janniklasrose, @lennartkats-db, @rugpanov, @rclarey) can approve all areas.
See OWNERS for ownership rules.}

[simonfaltum]

Superseded by #6684, recreated from a branch in databricks/cli so CI can access the required OIDC token.