Day 7, Parts 1 + 2

Doing this one in Rust kicked my ass. I fought with the compiler for three
days and never was able to figure out the borrows and pointers.

I gave up yesterday and wrote up a solution in Python. Maybe I'll come back to
it one day.

2022/Data/day7-test-input.txt

@@ -0,0 +1,23 @@
+$ cd /
+$ ls
+dir a
+14848514 b.txt
+8504156 c.dat
+dir d
+$ cd a
+$ ls
+dir e
+29116 f
+2557 g
+62596 h.lst
+$ cd e
+$ ls
+584 i
+$ cd ..
+$ cd ..
+$ cd d
+$ ls
+4060174 j
+8033020 d.log
+5626152 d.ext
+7214296 k