Update copyright year - #1502

It's already June, and we haven't updated the copyright year for 2022.

This PR:

• Updates copyright displayed to users (e.g. jrnl --version)
• Updates copyright year in each file (required by GPLv3)
• Adds missing copyright notices in some files
• Standardizes formatting for copyright notices throughout all files

Checklist

• I have read the contributing doc.
• I have included a link to the relevant issue number.
• I have checked to ensure there aren't other open pull requests
  for the same issue.
• I have written new tests for these changes, as needed.