make module override in subcommands a flag

[nikolubbe]

The module option was a positional argument for most commands, but that does not make sense to me because:

• You can set a default (the common use-case)
• If you omit the module, and do not have a default module set, you will be prompted to select a module to operate on
• The subcommands read something like this:
  kl services set-endpoint <module-name> <service-name> <"host" | "container">
  This read easier in my opinion:
  kl services set-endpoint <service-name> <"host" | "container> with the option to specify -m or --module to override

[julienvincent]

Makes sense to me