Add an option to mute / disable nodes

[rubberduck9999]

Having an option to mute nodes would be really great, for 2 reasons I describe below.

I searched for it here and tested if I find such a function in material maker, but wasn't able to find something like that.

The first is to quickly view the difference between the current setup and how it would look without that node.
For example you have node a and b, going into a blend node with a on top and b below, that goes in any other node (let's say it is the material output), muting the node would be like plugging the node a directly into the material output.

Another example would be to have a slope blur node and not a blend node to see how the input a looks without the blur effect in the material, without the need to temporary re-plug the node graph.
Such changes to the node graph also sometimes lead to setting up the graph later in the wrong way, not how I had it before and how I want it, leading to unneeded computation

The second reason though is much more important, and that is to save performance while editing, when having complex graphs, that in some cases make material maker really lagging. I recently had a setup using the scratches node together with some others, using them with the tile2x2 or variations node and a node like the tiler or splatter. This could also help to find areas in the node graph that can be optimized (meaning to find nodes that don't contribute much to the end result, but cost a lot of performance, and that could be improved by using a different workflow that leads to similar results and is much faster)

This should also prevent computing muted nodes or node graphs when clicking on it, this is another thing that could be really annoying, you click on a node you don't want and see the result in the 2d preview, while working on another nodes