Add support for mode field, with CurseForge metadata lookup

Now always asks the user before proceeding past the point where optional mods could be selected and configured
When updating files, the hash is checked so an update isn't redownloaded if it already exists
Added DevMain file for running in a dev environment

src/main/kotlin/link/infra/packwiz/installer/DevMain.kt

@@ -0,0 +1,5 @@
+package link.infra.packwiz.installer
+
+fun main(args: Array<String>) {
+	Main(args)
+}