supporting custom headers in generated PO files

Hi @grosser 👋🏼

I'd like to be able to customize the header output that's generated in PO files when running rake gettext:find. Currently there are some placeholder values like FIRST AUTHOR, COPYRIGHT HOLDER, FULL_NAME, etc:

# English translations for foo package.
# Copyright (C) 2021 THE PACKAGE'S COPYRIGHT HOLDER
# This file is distributed under the same license as the foo package.
# FIRST AUTHOR <EMAIL@ADDRESS>, 2021.
#
msgid ""
msgstr ""
"Project-Id-Version: github 1.0.0\n"
"Report-Msgid-Bugs-To: \n"
"PO-Revision-Date: 2021-01-22 21:21-0800\n"
"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
"\n"

I opened an issue on the ruby-gettext/gettext repo, where @kou pointed out that:

You need to add --translator, --translator-name=XXX, --translator-email=YYY options to msginit. It seems that https://github.com/grosser/gettext_i18n_rails/blob/master/lib/gettext_i18n_rails/tasks.rb provides APIs to add options to msgmerge, msgcat and xgettext but doesn't provide an API to add options to msginit.

Is this something you'd be open to adding support for in gettext_i18n_rails? If so, I'd be happy to help on it but might need a little guidance along the way.

cc @bigzoo @mjacbous @southgate

grosser / gettext_i18n_rails

supporting custom headers in generated PO files #184