Copilot: Add setting for automatic completion

Can be used to turn off the automatic completion insertion, so a user
only can request suggestions explicitly via the shortcut.

Change-Id: I0c4d9e2f41d30312b0870facdd80dc1d3d03d809
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>

src/plugins/copilot/copilotoptionspage.cpp

@@ -49,6 +49,7 @@ file from the Copilot neovim plugin.
             authWidget, br,
             CopilotSettings::instance().nodeJsPath, br,
             CopilotSettings::instance().distPath, br,
+            CopilotSettings::instance().autoComplete, br,
             helpLabel, br,
             st
         }.attachTo(this);