Move TOML code out of the configuration in core, and into fx.

core/src/main/kotlin/org/nwapw/abacus/config/Configuration.kt

@@ -0,0 +1,7 @@
+package org.nwapw.abacus.config
+
+open class Configuration(var numberImplementation: String = "<default>", disabledPlugins: Array<String> = emptyArray()) {
+
+    val disabledPlugins = disabledPlugins.toMutableSet()
+
+}