fix(optimizer): fold function aliases using resolved names

[yavon007]

Imported aliases could make constant folding execute the wrong string function. For example, use function strtoupper as upper; upper('MiXeD') compiled to "mixed" instead of "MIXED". The same issue affected case-sensitive and case-insensitive string comparisons.

Pass the resolved function name through constant-fold dispatch instead of reading the original AST alias. Add a PHPT covering both directions of case conversion and two-/three-argument comparison, including aliases that shadow another built-in name.

Validation on Linux ARM64 with PHP 8.5.10:

• New PHPT fails before the fix and passes afterward; its six expected results also match plain PHP.
• New PHPT and existing use-function-alias.phpt: 2 passed with native AOT compilation.
• FuncCallOptimizerTest and FuncCallOptimizerUnpackTest: 2 tests, 23 assertions passed.
• git diff --check passed.