Add --quiet-with-result flag

[Nezteb]

An alternative to --quiet that doesn't print any of the:

Finding suitable PLTs
Checking PLT...
[:amqp, :amqp10_client, :amqp10_common, :amqp_client, :argon2_elixir, :asn1, :bus, :castore, :certifi, :combine, :compiler, :configparser_ex, :connection, :cowboy, :cowboy_telemetry, :cowlib, :crypto, :db_connection, :decimal, :ecto, :ecto_sql, :eex, :elixir, :elixir_uuid, :ex_aws, :ex_aws_rds, :ex_aws_s3, :expo, :gettext, :gun, :hackney, :hierarch, :inets, :jason, :jsx, :kernel, :logger, :logger_json, :metrics, :mime, ...]
PLT is up to date!
No :ignore_warnings opt specified in mix.exs. Using default: .dialyzer_ignore.exs.

Starting Dialyzer
[
  check_plt: false,
  init_plt: '/Users/noah/Git/project/priv/plts/dialyzer.plt',
  files: ['/Users/noah/Git/project/_build/dev/lib/project/...',
   ...],
  warnings: [:underspecs, :unknown]
]

But does print:

Total errors: 207, Skipped: 207, Unnecessary Skips: 0
done (passed successfully)

[Nezteb]

I'm not a huge fan of this method, but since --quiet is implemented by changing the Mix shell, I couldn't think of a better way without drastically refactoring things.

[Nezteb]

When some versions of Elixir/Erlang run this test, they have different numbers of errors/skipped/etc, so I had to use a regex check.

[jeremyjh]

Hey, sorry for the delay responding. Looks good and thanks!