Support UTF-8 files with BOM encoding attached.

[zydeas]

As discussed in Discord:

I created a Lua file in Jetbrains Rider, and had the setting to include the BOM turned on. This resulted in Unreal importing the file with some garbage characters at the front, rather than handling those characters properly. This was only fixed by creating a new file after I'd turned the setting off.

The plugin should import files while excluding these characters.