Usability - provide template structures to help new users build menu trees

[davetcc]

To help new users, along with the AI system prompt, provide menu some basic structures that can be inserted directly into the current menu, these cover some regular cases that come up a lot.

There will be a button next to new item that will basically insert either a whole starter menu or a whole sub menu of items into a design.

It turns out that everything needed to do this is literally built in, and uses the same functionality exactly as copy and paste, and as a result, barely even needs testing.

Procedure:

1. Create the menu structure within a new designer session
2. Copy the items out of designer by selecting the top level menu and copying
3. Paste the items into a new file in generator's plugin/templates folder
4. Adjust the template class to include that new template

To start with we'll cover these cases:

Done:

• Core items for an Audio amplifier
• Core items for a bench PSU
• Submenu with items normally needed for IoT control
• Submenu with items normally used to monitor a battery
• Submenu with items normally used to control a motor.

Todo:

• Environmental controller menu
• Sensor dashboard
• Power Monitor/Energy meter
• 3D printer/CNC panel basic items
• Synthesizer/MIDI controller basic items