Optimize building and casting of EnsoMultiValue #145

Job	Run time
🔍 Files Changed / Changed Files	6s
⚙️ Checks / Engine (GraalVM CE) (windows, amd64)	10m 33s
⚙️ Checks / Engine (GraalVM CE) (linux, amd64)	4m 25s
⚙️ Checks / JVM Tests (GraalVM CE) (windows, amd64)	1h 15m 47s
⚙️ Checks / JVM Tests (GraalVM CE) (linux, amd64)	15m 26s
⚙️ Checks / Standard Library Tests (GraalVM CE) (linux, amd64)	21m 33s
⚙️ Checks / Standard Library Tests (GraalVM CE) (windows, amd64)	24m 11s
⚙️ Checks / Verify License Packages (linux, amd64)	33s
⚙️ Checks (Optional) / JVM Tests (GraalVM CE) (macos, amd64)	45m 53s
⚙️ Checks (Optional) / Engine (GraalVM CE) (macos, amd64)	36m 11s
⚙️ Checks (Optional) / Standard Library Tests (GraalVM CE) (macos, amd64)	35m 40s
Engine Required Checks	1s
	4h 30m 19s

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