Arbitrary vars in rule refs #8852

Job	Run time
Rego PR checks	2m 10s
Go Lint	2m 48s
Generate Code	1m 28s
Check Generated	2m 18s
Go compat build/test (ubuntu-22.04, 1.19)	4m 44s
Go compat build/test (macos-latest, 1.19)	4m 44s
Go Build (linux amd64)	3m 23s
Go Build (linux arm64)	3m 33s
Go Build (windows)	3m 51s
Go Build (darwin)	3m 30s
Go Race Detector	7m 49s
Go Test (linux)	7m 31s
Go Test (darwin)	10m 19s
WASM	11m 37s
docker image smoke test	35s
smoke-test-binaries (ubuntu-22.04, opa_linux_amd64)	23s
smoke-test-binaries (ubuntu-22.04, opa_linux_amd64_static, disabled)	23s
smoke-test-binaries (macos-latest, opa_darwin_amd64)	24s
smoke-test-binaries (windows-latest, opa_windows_amd64.exe)	46s
	1h 12m 16s

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