Improve how we handle flag subcommands in launcher

[RebeccaMahany]

We allow for calling launcher's version subcommand with both launcher version and launcher --version. We also have another flag, --dev_help, that functions as a subcommand rather than configuration.

This means we handle subcommands in two distinct locations. For the ones that are technically flags (--version, --dev_help), we handle them in pkg/launcher/options. For the actual subcommands, we handle them in launcher main's runSubcommands.

We would like to update how this currently works to achieve several goals:

1. Remove possibility for different behavior when calling "launcher version" versus "launcher --version." The split implementation means we have the possibility for different behavior in launcher version versus launcher --version. We should instead have one function that handles printing launcher version.
2. Code clarity. We have a workaround to ensure that launcher main exits instead of proceeding to runLauncher when launcher --version or launcher --dev_help is called, which is to return an InfoCmdError from options parsing if those flags are present; launcher main then handles that error by returning early. This is a little bit confusing to follow.

We see two potential paths to implementation:

1. Parse --version and --dev_help inside runSubcommands, ahead of options parsing, and handle them there; ignore them when options parsing inside pkg/launcher.
2. Embed the booleans inside launcher.Options in pkg/launcher/options and return them, then handle them in launcher main; remove InfoCmdError.

For more context, see the original discussion here: #1693 (comment)