Refactor item pipe model texture lookup

[alcox233]

Summary

• reuse ItemPipeType.VALUES when mapping restrictive pipe textures to base pipe textures
• avoid enum values() array cloning inside model texture lambdas
• add a regression script for the cached lookup

Test Plan

• powershell -ExecutionPolicy Bypass -File scripts/regression/item_pipe_values.ps1
• git diff --check
• ./gradlew.bat compileJava --no-daemon --console=plain