project: Switch to libhandy-1

This commit updates the dependencies for libhandy to the tagged 1.0
release and changes the code to accomodate the changes from
libhandy-0 to libhandy-1.

Notable changes:
edit-dialog: HdyDialog has been dropped in [1]
alarm-row: action child type in HdyActionRow has been removed.

[1] https://gitlab.gnome.org/GNOME/libhandy/-/merge_requests/434

build-aux/flatpak/org.gnome.Calendar.json

@@ -174,8 +174,8 @@
             "sources" : [
                 {
                     "type" : "git",
-                    "url" : "https://source.puri.sm/Librem5/libhandy.git",
-                    "branch" : "libhandy-0-0"
+                    "url" : "https://gitlab.gnome.org/GNOME/libhandy.git",
+                    "tag" : "1.0.0"
                 }
             ]
         },