build: We never have enough .in.in

This seems useless, but it's necessary for the next commit... or rather,
I really couldn't figure out a nice way to make next commit without
this.

I'm separating it in its own commit to make the next one easier to
review, but they really go together.
appdata: Add the appdata files for Cangjie and Quick

This also sets them up for translation.
components: Fix the XML files

Now that we're going through intltool for all our XML files, they need
to be formatted correctly.

That means the <xml> tag must be the first in the file.

Of course, these two files don't get translated, as IBus doesn't support
that for the component files... yet?
build: Drop obsolete line

Now tht we added data/ to BUILT_SOURCES, this became unneeded.