feat: Soft-assert mode for builtin out-params under not

- Add a scoped soft_assert_mode to the compiler so `not` statements compile their subexpressions without emitting hard AssertCondition/AssertNotUndefined instructions.
- Teach binding-plan application to return an optional result register; equality plans now yield a boolean in soft mode, allowing not abs(-5 , 3) to succeed instead of aborting.
- Update function-call, loop, and rule plumbing to consume the new binding-plan outcome, including copying the produced register when an out-parameter equality is used.
- Trim the OPA TODO list to the remaining troublesome folders.

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

src/languages/rego/compiler/program.rs

@@ -131,7 +131,7 @@ impl<'a> Compiler<'a> {
         if !self.program.builtin_info_table.is_empty() {
             self.program
                 .initialize_resolved_builtins()
-                .map_err(|err| CompilerError::from(err))?;
+                .map_err(CompilerError::from)?;
         }
 
         Ok(self.program)