fix: collapse ternary with the same constant in both branches

[obus-globus]

NOTE: This is what one may call "AI slop". Feel free to close this PR if it's not up to your quality standards or even if you just aren't interested in reviewing it. I use these changes downstream on an APK and thought I might as well make a PR offering to upstream them, as your CONTRIBUTING.md doesn't say anything discouraging this.

Description

if (c) return x; else return x; (and the assignment form) decompiled to a redundant c ? x : x, a ternary with the same constant in both branches, e.g. return apiException != null ? null : null;. It shows on every input path (dex and java/class alike): TernaryMod forms the ternary without noticing the two results are equal, and nothing removes it.

SimplifyVisitor.simplifyTernary (which already normalizes a ternary's condition) now also collapses c ? x : x to x when both value args are the same constant (InsnArg.isSameConst, covering int/null/string/class constants), for both the return-wrapped and assign-result forms.

Dropping the condition is only safe when evaluating it has no observable effect, so canDropCondition collapses only when every condition instruction is non-throwing and every operand is a parameter or a plain field read (IGET/SGET). foo() ? x : x and a[0] > 0 ? x : x are left as-is, and a cast operand is rejected so the erased CHECK_CAST behind String s = list.get(0) (and its ClassCastException) is never dropped.

This is scoped to same-constant branches. A same-value ternary (c ? v : v with the same variable) is left as-is.

Includes an integration test.