Service: add additional options

[SMillerDev]

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Adds some of the missing launchctl settings.

[BrewTestBot]

Review period will end on 2021-05-25 at 00:00:00 UTC.

[carlocab]

Can we also have an option to override the manual command, just like with plist_options manual:? Sometimes the command you want to run manually is different. See, for example, emacs.

[SMillerDev]

Not as part of this PR iyam, but I think that should be possible.

[BrewTestBot]

Review period ended.