PowerShell support

[Riari]

Hi,

Firstly, thank you so much for all the time and effort you've put into this plugin! I recently started migrating from VS Code to Neovim and Unreal was on my list of must-haves, so this has helped me out a lot.

I was just wondering if it could be updated to support PowerShell. Out of the box, any Dispatch commands issued by the plugin are misinterpreted by PowerShell. I'm not sure how exactly this should be handled, but I found a temporary workaround by replacing "Dispatch " with "Dispatch & " in lua/unreal/commands.lua.

Also, I had some difficulty with the :UnrealGenWithEngine / :UnrealGen commands - I couldn't get them to produce a compile_commands.json that works properly with clangd (using UE 5.4.4, tested on a fresh project). In the end, the only way I could get it to work was to generate the compilation database using the generate.bat script created by https://github.com/natsu-anon/ue-assist. Happy to open a separate issue about that if preferred.