cli/parser: improve name_to_option for some cask args

[Rylan12]

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---

Follow up to #10133

Previously (note that --input_methoddir is incorrectly displayed as --input-methoddir):

$ brew install --input_methoddir=abc --formula safe-rm
[...]
Error: Invalid usage: Options --formula and --input-methoddir are mutually exclusive.

Now (note the correct --input_methoddir flag is shown):

$ brew install --input_methoddir=abc --formula safe-rm
[...]
Error: Invalid usage: Options --formula and --input_methoddir are mutually exclusive.

CC @issyl0 and @reitermarkus

[BrewTestBot]

Review period will end on 2020-12-25 at 19:18:45 UTC.

[MikeMcQuaid]

Thanks @Rylan12! I think it'd be nice to update these flags to be consistent with the others eventually, though.

[Rylan12]

Agreed. I'll look into it.

[Rylan12]

This won't be needed if #10147 is merged, so putting on hold until a decision is made there.

[BrewTestBot]

Review period ended.

[Rylan12]

#10147 has been merged so this is no longer needed.