screenshot-ui: Add two key bindings from g-s-d

These two are moving into gnome-shell to unify screenshot handling and
allow for same-frame capturing.

While we're at it, move the keybindings .xml file from g-c-c here
because it belongs to gnome-shell.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2107>

data/50-gnome-shell-screenshots.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<KeyListEntries schema="org.gnome.shell.keybindings"
+                group="system"
+                name="Screenshots"
+                wm_name="GNOME Shell"
+                package="gnome-shell">
+
+    <KeyListEntry name="show-screenshot-ui"
+                  description="Take a screenshot interactively"/>
+
+    <KeyListEntry name="screenshot"
+                  description="Take a screenshot"/>
+
+    <KeyListEntry name="screenshot-window"
+                  description="Take a screenshot of a window"/>
+
+</KeyListEntries>

data/meson.build

@@ -79,6 +79,7 @@ configure_file(
 
 keybinding_files = [
   '50-gnome-shell-launchers.xml',
+  '50-gnome-shell-screenshots.xml',
   '50-gnome-shell-system.xml',
 ]
 

data/org.gnome.shell.gschema.xml.in

@@ -232,7 +232,15 @@
     </key>
     <key name="show-screenshot-ui" type="as">
       <default>["Print"]</default>
-      <summary>Show screenshot UI</summary>
+      <summary>Take a screenshot interactively</summary>
+    </key>
+    <key name="screenshot-window" type="as">
+      <default>["&lt;Alt&gt;Print"]</default>
+      <summary>Take a screenshot of a window</summary>
+    </key>
+    <key name="screenshot" type="as">
+      <default>["&lt;Shift&gt;Print"]</default>
+      <summary>Take a screenshot</summary>
     </key>
   </schema>