Vendor org.graalvm.collections

[translatenix]

Motivation: Package org.graalvm.collections is used throughout the Pkl codebase. It is most heavily used in the Truffle interpreter, which requires putting most collection methods behind @TruffleBoundary. At the moment, this is done by wrapping collection methods with static methods declared in classes EconomicMaps and EconomicSets. However, static wrapper methods are inconvenient to use, decrease code readability, add some overhead, and are easy to forget about.

Changes:

• vendor package org.graalvm.collections into org.pkl.core.collection
  • org.graalvm.collections is licensed under: The Universal Permissive License (UPL), Version 1.0
  • vendored version: https://github.com/oracle/graal/tree/graal-23.0.3/sdk/src/org.graalvm.collections/src/org/graalvm/collections
  • add package-info.java with original license
  • annotate most public methods with @TruffleBoundary
  • add @Nullable annotations
  • switching to JSpecify will enable more accurate nullability checks
  • remove prefix tree classes (not used in Pkl)
  • make no other code changes to simplify review/updates
• inline and remove EconomicMaps/Sets wrapper methods
• replace usages of EconomicMaps.equals/hashCode with EconomicMapUtil.equals/hashCode
• fix ProjectDeps.hashCode()

Result: Cleaner, safer, and more efficient code.

[bioball]

I am not sure we want to do this. This makes it hard to upgrade the collections library, and I'm not sure how much of a performance gain we get out of this.

and are easy to forget about

Thankfully, our CI builds (on main) will catch these errors if they are forgotten.

Curious about @holzensp and @stackoverflow's thoughts