Add tab completion for loading schematics

[Josh65-2201]

The Problem

Currently i can only use /schematic list to see whats in there but then have to type it in manually

A Solution

Add tab completetion for all available schmatic shown in the list command

Alternatives

No response

Anything Else?

No response

[me4502]

This would be incredibly taxing on the filesystem

[Josh65-2201]

would it be any worse then just getting it the same way list command does?. maybe it could disable if there were more than a cirtain amount.

[wizjany]

the list command doesn't run dozens of times a second.

i have previously investigated caching the list and using that to generate suggestions but never got far with it.

[me4502]

added in #2542