[enhancement] String Concat Node, String List Node

It would be extremely helpful to have a node that can concatenate input strings, and also a way to load strings from text files.
This is not the same as putting both of the strings into one conditioning input, so proper string concatenation is something I really seek in stable diffusion GUIs, because it would allow parts of the positive/negative prompts to be stored and re-used easily while editing through various prompts.

Currently, it's always a hodgepodge that encourages endless addendums.

Instead of a comma-separated fluid prompt, splitting this up into a list of strings and then concatenating them in a way that the CLIP conditioning understands it later, would also help remove duplicates, iterate on orders and weights, etc.