Leading zero padding on output filenames

[zackdotcomputer]

Resolves #89 by adding leading zero padding the index number on saved filenames so that all index numbers in a batch are the same string length. This fixes ls ordering and * glob ordering of the collected files.

Also switches ffmpeg stitcher to using * glob selection rather than %d selection to remain compatible with that new numbering.

[JonnyBurger]

Works wonderfully! Thanks a lot for the PR 💙

This will be in the next release, likely coming out tomorrow, or you can upgrade to the prerelease right now, hope the little roadbump didn't slow you down too much!

 - @remotion/bundler@1.3.0-alpha.ca2e3e45
 - @remotion/cli@1.3.0-alpha.ca2e3e45
 - remotion@1.3.0-alpha.ca2e3e45
 - create-video@1.3.0-alpha.ca2e3e45
 - @remotion/eslint-config@1.3.0-alpha.ca2e3e45
 - @remotion/eslint-plugin@1.3.0-alpha.ca2e3e45
 - @remotion/renderer@1.3.0-alpha.ca2e3e45

[zackdotcomputer]

👍 not a problem at all. I really like the tool and am happy to help make it better.