We added the `--all` flag (now renamed to `--eval-all`) for various
commands for this behaviour so let's start deprecating this.
Also, introduce a `HOMEBREW_EVAL_ALL` environment variable to use the
existing, less secure, behaviour by default and avoid passing
`--eval-all` everywhere.
From reading https://github.com/orgs/Homebrew/discussions/3328: I
initially thought we should just change "Updated" to "Modified" when
appropriate. After conversation with Bo98, though, I thought more and
saw that we're already checking for outdated formulae here so, rather
than ever traverse through the formula history, look at the outdated
formula and list them unless we've set
`HOMEBREW_UPDATE_REPORT_ALL_FORMULAE` in which case we show the
modifications.
While we're here, also do a bit of reformatting and renaming to better
clarify intent.
Don't perform an incremental update from a report or list of formulae if
the cache is currently empty.
Also, remove some accidentally remaining debugging output.
This makes use of both the existing interfaces and could use the
existing cache file but we'll create a new one and cleanup the old one
to avoid issues and use a more consistent name.
