Add Tool Selection Menu for Multi-Extruder Printers

[DXCanas]

Second in series of changes made while setting up an FFCP, starting with #7247

I was excited to see filament loading was in the display menu. But then disappointed to see it only worked for the right extruder (which doesn't even have a fan in stock config)

So I threw together these macros for the display, as many of the options assume a single extruder

AI Assisted Summary: Add Tool Selection Menu for Multi-Extruder Printers

This PR adds a top-level "Tool" menu to the default display menu system that allows users with multi-extruder printers to switch between T0 and T1 directly from the LCD display.

Problem Statement

Users with dual-extruder printers (e.g., FlashForge Creator Pro, Prusa MMU setups, IDEX systems) currently cannot change the active tool from the display menu by default. This creates a usability gap when performing common operations:

• Filament operations (load/unload) always apply to the active extruder, but there's no display-based way to switch tools
• Manual extrusion via the Move menu operates on the active extruder only
• Temperature presets (Preheat PLA/ABS) apply M104 commands without T parameter, affecting only the active tool

Users must either use console commands (T0/T1) or remain connected to a host interface to switch tools, which can be impractical when working at the printer.

Solution

Added a conditional top-level menu between "SD Card" and "Control" that:

• Appears only when extruder1 is defined in the configuration
• Shows the currently active tool in the menu label ("Tool: T0" or "Tool: T1")
• Provides submenu options to activate T0 or T1
• Changes system-wide active extruder state for all subsequent menu operations

Target Audience

Multi-extruder printer users, including:

• FlashForge Creator Pro (2016-2020 models) - Several thousand units in active use
• Dual-extruder Cartesian printers - Various models with independent or IDEX toolheads
• Multi-material systems - Prusa MMU and similar configurations

Estimated user base (this requires confirmation) is large.

Testing

Tested on FlashForge Creator Pro 2019 with LCD display:

• Menu appears only when both extruder and extruder1 are defined
• Tool switching commands execute correctly (T0/T1)
• Active tool label updates dynamically after selection
• Filament load/unload operations correctly target the selected extruder
• No impact on single-extruder configurations (menu hidden via enable condition)

Implementation Details

• Follows existing menu conditional patterns (similar to z_tilt, quad_gantry_level)
• Parent menu uses enable: {'extruder1' in printer} condition
• Child menu items inherit parent visibility (standard menu.py behavior)
• No configuration changes required - automatically available when extruder1 is present

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