feat: add while loops, break and continue statements

tests/while_break_continue.src

@@ -0,0 +1,20 @@
+fn main() -> i32 {
+    let i = 0;
+    let sum = 0;
+
+    while i < 10 {
+        i = i + 1;
+
+        if i % 2 == 0 {
+            continue;
+        }
+
+        if i > 7 {
+            break;
+        }
+
+        sum = sum + i;
+    }
+
+    return sum;
+}