ZKR-1371-Update-Abstract-Interpretation-Code

[FatemehHeidari]

There are some minor changes related to removing some TODOs and deleting an unused line of code.

And also a question from second round of code review:

This is more of a question then a suggestion. In the below function, do we intend on counting RegionColumn::Selector? I'm asking because in that case used == false but we call continue which skips the counting.
pub fn analyze_unconstrained_cells(&mut self) -> Result {
let mut count = 0;
for region in self.layouter.regions.iter() {
let selectors = HashSet::from_iter(region.selectors().into_iter());

        for (reg_column, rotation) in region.columns.iter().cloned() {
            let mut used = false;

            match reg_column {
                RegionColumn::Selector(_) => continue,
                RegionColumn::Column(column) => {
                    for gate in self.cs.gates.iter() {
                        for poly in gate.polynomials() {
                            let advices = abstract_expr::extract_columns(poly);
                            let eval = abstract_expr::eval_abstract(poly, &selectors);

                            column.index(); // <<<<<<<<<<<<<<<<<<<<<

                            if eval != AbsResult::Zero && advices.contains(&(column, rotation))
                            {
                                used = true;
                            }
                        }
                    }
                }
            };

            if !used {
                count += 1;
                self.log.push(format!("unconstrained cell in \"{}\" region: {:?} (rotation: {:?}) -- very likely a bug.", region.name,  reg_column, rotation));
            }
        }
    }

[jgorzny]

This appears to be a real todo; I will push a commit to check our internal ticket and re-add the todo.