Implement gawk array sorting and type-introspection builtins

[bertysentry]

Problem

This is a focused follow-up to umbrella issue #80. The latest mvn verify run for GawkCompatibilityIT shows a concrete compatibility cluster around gawk's array sorting and type-introspection features.

Observed impact:

• 13 failing Gawk compatibility cases in the latest run
• Representative cases: asort, asorti, aasort, aasorti, asortbool, asortsymtab, sort1, arraytype, mdim1, typeof2, typeof4, typeof5, typeof6
• Current failure mode is typically SemanticException: function ... (asort|asorti|typeof)

The failing cases suggest that we need more than stub builtin registration. Jawk also needs the corresponding runtime behavior that gawk expects for:

• asort()
• asorti()
• typeof()
• typed / untyped / array value distinctions that those functions expose

Specification

Read how asort() and asorti() functions works.

Read how typeof() function works

Implement these in a builtin Jawk extension, named GawkExtension. Make it enabled by default (when no extensions are specified by the caller, and notably in the Cli).

Acceptance criteria:

• the representative cases above pass in GawkCompatibilityIT
• asort() and asorti() work on plain arrays and nested arrays where gawk allows them (and also Java Map and List)
• typeof() returns gawk-compatible categories for the cases covered by the suite
• sorting and introspection behavior is wired into the real runtime model, not only the parser