[xdg-desktop-portal-gnome] Add libadwaita as a Meson wrap

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit daf1e3b3fdf6e433ce9ded0e8231ede5278af8b3
Author: Tristan Partin <tristan partin io>
Date:   Mon Jun 21 15:23:07 2021 -0500

    Add libadwaita as a Meson wrap
    
    Wraps are easier to work with than Git submodules and Meson has built-in
    support for them.

 .gitignore                  | 2 ++
 .gitmodules                 | 3 ---
 subprojects/libadwaita      | 1 -
 subprojects/libadwaita.wrap | 3 +++
 4 files changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/.gitignore b/.gitignore
index dec5a77..c104686 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,5 @@ src/views/.dirstamp
 .gitlab
 .flatpak-builder
 **/*~
+/subprojects/*
+!/subprojects/libadwaita.wrap
diff --git a/subprojects/libadwaita.wrap b/subprojects/libadwaita.wrap
new file mode 100644
index 0000000..a0c0609
--- /dev/null
+++ b/subprojects/libadwaita.wrap
@@ -0,0 +1,3 @@
+[wrap-git]
+url = https://gitlab.gnome.org/GNOME/libadwaita.git
+revision = main