GROOVY-12257: Restore ObjectUtil as a binary-compatibility facade for…

[paulk-asert]

… Groovy 4 compiled @immutable classes

The @immutable transform in Groovy 4.0.5 through 4.0.x (GROOVY-10747) emitted references to org.apache.groovy.runtime.ObjectUtil.cloneObject into generated constructors and getters for defensive copies. The class was removed along with the $getLookup machinery it relied on (GROOVY-10931), so such pre-compiled classes fail on Groovy 5+ with NoClassDefFoundError at first instantiation — only when a clone path actually executes, which for collection properties depends on the runtime value being Cloneable, making the failure intermittent.

Restore the class as a deprecated facade with the original semantics minus the lookup dependency: null passes through, non-Cloneables throw CloneNotSupportedException, arrays clone via the unchanged ArrayUtil fast paths, and other Cloneables clone through their public clone() via the MOP (guarded by the same getMethod check as the original, so a non-public clone() still surfaces NoSuchMethodException). Nothing compiled by Groovy 5+ references the class; current transforms emit indy or InvokerHelper clone calls instead.

Verified against real Groovy 4.0.33 bytecode: the reproducer's List property shape and the unconditional array/getter shape both fail with NoClassDefFoundError before this change and pass with it, preserving defensive-copy semantics.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 92.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.1276%. Comparing base (142130d) to head (10b3130).
⚠️ Report is 7 commits behind head on master.

Files with missing lines	Patch %	Lines
...ain/java/org/apache/groovy/runtime/ObjectUtil.java	92.0000%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##               master      #2788        +/-   ##
==================================================
+ Coverage     70.1064%   70.1276%   +0.0212%     
- Complexity      35774      35799        +25     
==================================================
  Files            1561       1562         +1     
  Lines          132373     132400        +27     
  Branches        24332      24345        +13     
==================================================
+ Hits            92802      92849        +47     
+ Misses          31170      31156        -14     
+ Partials         8401       8395         -6     

Files with missing lines	Coverage Δ
...ain/java/org/apache/groovy/runtime/ObjectUtil.java	92.0000% <92.0000%> (ø)

... and 7 files with indirect coverage changes

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