Rename Project Euler directories and other dependent changes (#3300)

* Rename all Project Euler directories:

Reason:
The change was done to maintain consistency throughout the directory
and to keep all directories in sorted order.

Due to the above change, some config files had to be modified:
'problem_22` -> `problem_022`

* Update scripts to pad zeroes in PE directories

project_euler/problem_040/sol1.py

@@ -0,0 +1,45 @@
+"""
+Champernowne's constant
+Problem 40
+An irrational decimal fraction is created by concatenating the positive
+integers:
+
+0.123456789101112131415161718192021...
+
+It can be seen that the 12th digit of the fractional part is 1.
+
+If dn represents the nth digit of the fractional part, find the value of the
+following expression.
+
+d1 × d10 × d100 × d1000 × d10000 × d100000 × d1000000
+"""
+
+
+def solution():
+    """Returns
+
+    >>> solution()
+    210
+    """
+    constant = []
+    i = 1
+
+    while len(constant) < 1e6:
+        constant.append(str(i))
+        i += 1
+
+    constant = "".join(constant)
+
+    return (
+        int(constant[0])
+        * int(constant[9])
+        * int(constant[99])
+        * int(constant[999])
+        * int(constant[9999])
+        * int(constant[99999])
+        * int(constant[999999])
+    )
+
+
+if __name__ == "__main__":
+    print(solution())