Flags for failure handling

[onyxraven]

Story/Issue Link

4 Clean should not error

8 Cleanup during add/remove

... and more

Background

Taking care of a couple related tickets.

New features:

• flag to not fail on decrypt/entrypoint if not all the files can be decrypted
  • use case: files with differing key scopes (eg prod vs stage)
• allow sopstool to be called when .sops.yml isn't in the ancestry
  • for completion, help, etc
• cat can print multiple files
  • you know, like cat
• cleanup if a decrypt fails
  • it was leaving behind an empty file

Versioning

Minor release

Additional Requests to Reviewers

Some of the changes are not super testable yet because mocking commands isn't possible

Tasks

• [x] Specs written
• [x] Manual testing

/cc