Precompiler doesn't take directories as input

Hey,

I'm trying to use a directory (with subdirectories) as source for the handlebars cli, but every time I use a valid directory (e.g. `handlebars test/ -f out.js`) it just returns the help/usage advice.

Since the help states `Usage: handlebars [template|directory]...` I expected the command above to work. I'm on handlebars 4.7.8.

Best
anghenfil

Start by reproducing `handlebars test/ -f out.js` with Handlebars 4.7.8, then inspect the CLI precompiler entry point that parses template and directory arguments. Trace why a valid directory falls through to usage output; done means directory input, including subdirectories, compiles successfully and the behavior is covered by a regression test.

Written by the indexing model from the issue text.