Given a list of lowercase strings, find the length of the longest possible chain of words where each word in the chain is formed by inserting exactly one character into the previous word (at any position). Each word in the chain must appear in the given list. Return an integer representing the maximum chain length. Example: ['a', 'ab', 'abc'] has a longest chain length 3.
['a', 'ba', 'bca', 'bda', 'bdca']4