Normalize DataSource key

Fixes wpilibsuite#820

Author: sciencewhiz

plugins/networktables/src/main/java/edu/wpi/first/shuffleboard/plugin/networktables/sources/NetworkTableSource.java

@@ -209,7 +209,7 @@ public static void removeAllCachedSources() {
    */
   @SuppressWarnings("unchecked")
   public static DataSource<?> forKey(String fullTableKey) {
-    String key = fullTableKey;
+    String key = NetworkTable.normalizeKey(fullTableKey, false);
     final String uri = NetworkTableSourceType.getInstance().toUri(key);
     return sources.computeIfAbsent(uri, __ -> {
       DataType<?> lookup = NetworkTableUtils.dataTypeForEntry(key);