Pads a string on the left to a specified length.
StringPadLeft["string", n]
StringPadLeft["string", n, "padding"]
StringPadLeft[{"s1", "s2", …}]
StringPadLeft[{"s1", "s2", …}, n, …]
StringPadLeft["hi", 5]
→ hiStringPadLeft["hi", 5, "0"]
→ 000hiStringPadLeft["hello", 3]
→ lloStringPadLeft[{"a", "ab", "abc"}]
→ { a, ab, abc}