docs: Stop hiding the Unix-like APIs which are in Gio-2.0.gir

There are four `Unix.+` classes in `Gio-2.0.gir` which need to be
exposed in the `Gio-2.0.gir` docs because they are actually now
cross-platform (which is a move which has caused a lot of pain).

Change the code which filters out the rest of the `Unix.+` classes to
ignore these ones. The rest of the classes continue to be documented via
`GioUnix-2.0.gir`.

Changing the regexs for this involved a fun use of negative lookahead.

See https://gitlab.gnome.org/GNOME/glib/-/issues/3697#note_2459405

Signed-off-by: Philip Withnall <pwithnall@gnome.org>
Helps: #3697

docs/reference/gio/gio.toml.in

@@ -79,20 +79,27 @@ content_images = [
 # We have to hide the GioUnix and GioWin32 symbols from the documentation — they
 # have to be present in the GIR files (until we next break API), but their
 # documentation is split out to gio-{unix,win32}.toml.
+#
+# There are four exceptions, which are ‘Unix’ APIs which are legitimately in
+# the main Gio library as they can now be used on Windows:
+#  - GUnixConnection
+#  - GUnixCredentialsMessage
+#  - GUnixFDList
+#  - GUnixSocketAddress
 [[object]]
-pattern = "Unix[A-Z].+"
+pattern = "Unix(?!Connection|CredentialsMessage|FDList|SocketAddress).+"
 hidden = true
 
 [[object]]
-pattern = "unix_.+"
+pattern = "unix_(?!connection|credentials_message|fd_list|socket_address).+"
 hidden = true
 
 [[struct]]
-pattern = "Unix[A-Z].+"
+pattern = "Unix(?!Connection|CredentialsMessage|FDList|SocketAddress).+"
 hidden = true
 
 [[function]]
-pattern = "unix_.+"
+pattern = "unix_(?!connection|credentials_message|fd_list|socket_address).+"
 hidden = true
 
 [[object]]