Add keyboard shorcuts to focus and unfocus chat (#3898)

* Added keyboard shorcuts to focus and unfocus chat

* Fixed format

* Changed the Esc behavior to work on any QLineEdit in the main Window and ignore shortcut conflicts

* Fixed a conflict with shortcuts

* Configurable unfocus shortcut and format fixes

* minor style fix

cockatrice/src/customlineedit.h

@@ -0,0 +1,27 @@
+
+#ifndef CUSTOMLINEEDIT_H
+#define CUSTOMLINEEDIT_H
+
+#include <QLineEdit>
+
+class QKeyEvent;
+class QWidget;
+class QString;
+
+// Should be used when the there is a risk of conflict between line editor
+// shortcuts and other shortcuts
+class LineEditUnfocusable : public QLineEdit
+{
+public:
+    LineEditUnfocusable(QWidget *parent = nullptr);
+    LineEditUnfocusable(const QString &contents, QWidget *parent = nullptr);
+
+private:
+    bool isUnfocusShortcut(QKeyEvent *key);
+
+protected:
+    void keyPressEvent(QKeyEvent *event) override;
+    bool eventFilter(QObject *watched, QEvent *event) override;
+};
+
+#endif