Refactor display-related flags

[PsypherPunk]

Currently we have 3 options which in various ways modify the way we display output:

• --greppable: minimal output
• --accessible: alters some of the output effects
• --no-banner: removes the banner

As these are specific to varying degrees but all affect the output, I'd like to suggest refactoring them into a single flag: --display, i.e.

• --display greppable|minimal
• --display accessible
• --display no-banner

Presumably this would be part of a major-change as it would be a breaking change to the CLI tool's contract.