server: Use formatx for translatable strings

[A6GibKm]

See https://www.gnu.org/software/gettext/manual/html_node/Rust.html.

This requires xgettext 0.24, otherwise the translatable strings won't be extracted.

Can be tested with meson compile -C $builddir oo7-daemon-pot.

[A6GibKm]

Given that the generated pot file is super small ill just paste it here:

#: src/gnome/prompter.rs:139
msgid "Unlock Keyring"
msgstr ""

#: src/gnome/prompter.rs:140
msgid "Authentication required"
msgstr ""

#: src/gnome/prompter.rs:143
#, rust-format
msgid "An application wants access to the keyring '{}', but it is locked"
msgstr ""

#: src/gnome/prompter.rs:154
msgid "Unlock"
msgstr ""

#: src/gnome/prompter.rs:155 src/gnome/prompter.rs:177
msgid "Cancel"
msgstr ""

#: src/gnome/prompter.rs:161
msgid "New Keyring Password"
msgstr ""

#: src/gnome/prompter.rs:162
msgid "Choose password for new keyring"
msgstr ""

#: src/gnome/prompter.rs:165
#, rust-format
msgid ""
"An application wants to create a new keyring called '{}'. Choose the "
"password you want to use for it."
msgstr ""

#: src/gnome/prompter.rs:176
msgid "Create"
msgstr ""