Tighten up the validation of application IDs so they are always exactly
D-Bus well-known names. This is a slight change to the accepted format,
but since anyone using the API with an application ID which was
previously valid, but which was not a valid D-Bus well-known name, would
have received an error from D-Bus when their application tried to
register on the bus, I think this break is acceptable.

It will affect any applications which have application IDs which are not
valid D-Bus well-known names, and which use the G_APPLICATION_NON_UNIQUE
flag. From a quick search in Debian Codesearch, no C applications use
that flag.

Update the documentation to use the rules from the D-Bus specification,
including the latest advice discouraging use of hyphens:

https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names-bus



Update the tests:
 • Add the examples from the documentation to validate them.
 • Especially the venerable 7-zip.org example.
 • Move a couple of tests from expected-failure to expected-success:
   they are valid D-Bus well-known names even if they’re a bit weird.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

https://bugzilla.gnome.org/show_bug.cgi?id=793400