feat(gen_uplc): introduce scope new type

* new module scope which holds some ancestor logic
* rework some things to truly hide scope increments

Co-authored-by: Kasey White <kwhitemsg@gmail.com>

crates/aiken-lang/src/gen_uplc/scope.rs

@@ -0,0 +1,65 @@
+#[derive(Debug, Clone, Default)]
+pub struct Scope(Vec<u64>);
+
+impl Scope {
+    pub fn push(&mut self, value: u64) {
+        self.0.push(value);
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+
+    pub fn replace(&mut self, pattern: &Scope, replacement: Scope) {
+        let mut result = Vec::new();
+
+        let mut index = 0;
+        let mut pattern_index = 0;
+
+        let mut no_matches = true;
+
+        while index < self.0.len() {
+            if self.0[index] == pattern.0[pattern_index] {
+                if pattern_index == pattern.0.len() - 1 {
+                    no_matches = false;
+                    result.extend(replacement.0.clone());
+                    pattern_index = 0;
+                } else {
+                    pattern_index += 1;
+                }
+            } else {
+                result.push(self.0[index]);
+                pattern_index = 0;
+            }
+
+            index += 1;
+        }
+
+        if no_matches {
+            replacement.0.extend(self.0);
+            self.0 = replacement.0;
+        } else {
+            self.0 = result;
+        }
+    }
+
+    pub fn common_ancestor(&self, other: &Self) -> Scope {
+        let longest_length = self.0.len().max(other.0.len());
+
+        if *self.0 == *other.0 {
+            return self.clone();
+        }
+
+        for index in 0..longest_length {
+            if self.0.get(index).is_none() {
+                return self.clone();
+            } else if other.0.get(index).is_none() {
+                return other.clone();
+            } else if self.0[index] != other.0[index] {
+                return Scope(self.0[0..index].to_vec());
+            }
+        }
+
+        Scope::default()
+    }
+}