feat: click support for 'statusline', 'winbar' #18650

The mouseclick item "%@" is now supported by 'statusline' and 'winbar'.
Previously it was only supported by 'tabline'.

src/nvim/grid_defs.h

@@ -111,4 +111,22 @@ struct ScreenGrid {
                            false, 0, 0, NULL, false, true, 0, \
                            0, 0, 0, 0, 0,  false }
 
+/// Status line click definition
+typedef struct {
+  enum {
+    kStlClickDisabled = 0,  ///< Clicks to this area are ignored.
+    kStlClickTabSwitch,     ///< Switch to the given tab.
+    kStlClickTabClose,      ///< Close given tab.
+    kStlClickFuncRun,       ///< Run user function.
+  } type;      ///< Type of the click.
+  int tabnr;   ///< Tab page number.
+  char *func;  ///< Function to run.
+} StlClickDefinition;
+
+/// Used for tabline clicks
+typedef struct {
+  StlClickDefinition def;  ///< Click definition.
+  const char *start;       ///< Location where region starts.
+} StlClickRecord;
+
 #endif  // NVIM_GRID_DEFS_H