[keyboard] Add kwin-specific configuration flag

Running `kwin_wayland --locale1` makes KWin listen to locale1
for keyboard updates, but not everybody has that. Introduce a
KWin-specific configuration flag that will (re)write the
KWin configuration.

src/modules/keyboard/Config.cpp

@@ -714,6 +714,11 @@ Config::setConfigurationMap( const QVariantMap& configurationMap )
     m_convertedKeymapPath = getString( configurationMap, "convertedKeymapPath" );
     m_configureEtcDefaultKeyboard = getBool( configurationMap, "writeEtcDefaultKeyboard", true );
     m_configureLocale1 = getBool( configurationMap, "useLocale1", !isX11 );
+
+    bool bogus = false;
+    const auto configureItems = getSubMap( configurationMap, "configure", bogus );
+    m_configureKWin = getBool( configureItems, "kwin", false );
+
     m_guessLayout = getBool( configurationMap, "guessLayout", true );
 }
 

src/modules/keyboard/Config.h

@@ -121,6 +121,7 @@ private:
     bool m_configureXkb = true;
     bool m_configureEtcDefaultKeyboard = true;
     bool m_configureLocale1 = false;
+    bool m_configureKWin = false;
     bool m_guessLayout = false;
 
     // The state determines whether we guess settings or preserve them:

src/modules/keyboard/keyboard.conf

@@ -31,3 +31,15 @@ convertedKeymapPath: "/lib/kbd/keymaps/xkb"
 # Guess the default layout from the user locale. If false, keeps the current
 # OS keyboard layout as the default (useful if the layout is pre-configured).
 #guessLayout: true
+
+# Things that should be configured.
+configure:
+    # Configure KWin (KDE Plasma) directly by editing the
+    # configuration file and informing KWin over DBus. This is
+    # useful in a system that uses Wayland but does **not** connect
+    # locale1 with KWin.
+    #
+    # Systems that use KDE Plasma Wayland and locale1 can instead start the
+    # compositor KWin with command-line argument `--locale1`. That
+    # argument makes this configuration option unnecessary.
+    kwin: false

src/modules/keyboard/keyboard.schema.yaml

@@ -11,4 +11,9 @@ properties:
     writeEtcDefaultKeyboard: { type: boolean, default: true }
     useLocale1: { type: boolean, default: false }
     guessLayout: { type: boolean, default: true }
+    configure:
+        additionalProperties: false
+        type: object
+        properties:
+            kwin: { type: boolean, default: false }
 required: [ xOrgConfFileName, convertedKeymapPath ]