fix: support --version option

[ronnnnn]

Overview

1. Although the output of printHelp included a description of the --version flag¹, it was not supported, so I added it.
2. Since the results of the -V and -h flags generally terminate with exit 0, I modified the exit status accordingly.

Footnotes

1. /~https://github.com/ysugimoto/falco/blob/8ec8d6b9d3f0f4d68575da2d34ff2dc69c3583b8/cmd/falco/help.go#L65 ↩

[ysugimoto]

Thanks!
Yes the version and help command generally exit with 0, you're right.