Improve MMU toolchange when E-cool mode is enabled

Currently we are queuing many small 2 mm E-moves until the filament
sensor triggers. We do this because we never abort any queued moves,
so making small 2 mm moves ensures we do not move the E-motor more than
2 mm past the filament sensor.

Unfortunately, when E-cool mode is enabled, the E-motor will create
audible clicking sounds (similar one hears during jam or a loose grub
screw). A workaround for this is to queue one or more very long moves.
Where very long is something of the order of hundreds of millimeters. I
have it set to 350 mm but it's just a random constant really. Keep in
mind the firmware will block too large E-moves, if I recall correctly
it was anything above > 450 mm (see PREVENT_LENGTHY_EXTRUDE)

In order to use very long moves, we must somehow stop the E-motor from
moving once the filament sensor triggers. In other words, throw away
what's left of the current E-motor move. For this simple purpose we can
use planner_abort_hard() but we must set planner_aborted to false
afterwards because the code architecture does not allow the main loop()
to run until the Toolchange command is done processing.

Change in memory:
Flash: +18 bytes
SRAM: 0 bytes

Firmware/mmu2.cpp

@@ -922,10 +922,12 @@ void MMU2::ReportError(ErrorCode ec, ErrorSource res) {
     switch (logic.Progress()) {
     case ProgressCode::UnloadingToFinda:
         unloadFilamentStarted = false;
+        planner_abort_queued_moves();  // Abort excess E-moves to be safe
         break;
     case ProgressCode::FeedingToFSensor:
         // FSENSOR error during load. Make sure E-motor stops moving.
         loadFilamentStarted = false;
+        planner_abort_queued_moves(); // Abort excess E-moves to be safe
         break;
     default:
         break;
@@ -1040,6 +1042,10 @@ void MMU2::OnMMUProgressMsgSame(ProgressCode pc) {
             case FilamentState::AT_FSENSOR:
                 // fsensor triggered, finish FeedingToExtruder state
                 loadFilamentStarted = false;
+
+                // Abort any excess E-move from the planner queue
+                planner_abort_queued_moves();
+
                 // After the MMU knows the FSENSOR is triggered it will:
                 // 1. Push the filament by additional 30mm (see fsensorToNozzle)
                 // 2. Disengage the idler and push another 2mm.
@@ -1048,7 +1054,7 @@ void MMU2::OnMMUProgressMsgSame(ProgressCode pc) {
             case FilamentState::NOT_PRESENT:
                 // fsensor not triggered, continue moving extruder
                 if (!planner_any_moves()) { // Only plan a move if there is no move ongoing
-                    MoveE(2.0f, MMU2_LOAD_TO_NOZZLE_FEED_RATE);
+                    MoveE(350.0f, MMU2_LOAD_TO_NOZZLE_FEED_RATE);
                 }
                 break;
             default:

Firmware/mmu2_marlin.h

@@ -26,6 +26,7 @@ void MoveE(float delta, float feedRate);
 
 float MoveRaiseZ(float delta);
 
+void planner_abort_queued_moves();
 void planner_synchronize();
 bool planner_any_moves();
 float planner_get_machine_position_E_mm();

Firmware/mmu2_marlin1.cpp

@@ -18,6 +18,11 @@ float MoveRaiseZ(float delta) {
     return raise_z(delta);
 }
 
+void planner_abort_queued_moves() {
+    planner_abort_hard();
+    planner_aborted = false;
+}
+
 void planner_synchronize() {
     st_synchronize();
 }