feat: Standardize configs + create config mappers

Relates to #25 (closed)

src/main/java/org/eclipsefoundation/uss/config/ApplicationTokenFilterConfig.java

+/*********************************************************************
+* Copyright (c) 2023 Eclipse Foundation.
+*
+* This program and the accompanying materials are made
+* available under the terms of the Eclipse Public License 2.0
+* which is available at https://www.eclipse.org/legal/epl-2.0/
+*
+* Author: Zachary Sabourin <zachary.sabourin@eclipse-foundation.org>
+*
+* SPDX-License-Identifier: EPL-2.0
+**********************************************************************/
+package org.eclipsefoundation.uss.config;
+
+import java.util.Map;
+
+import io.smallrye.config.ConfigMapping;
+import io.smallrye.config.WithDefault;
+
+/**
+ * Loads all ApplicationTokenFilter properties. Contains an enabled
+ * flag, as well as a list of allowed application tokens. These configs can be
+ * modified by updating the '/main/resources/application.properties' or
+ * '/test/resources/application.properties' files.
+ */
+@ConfigMapping(prefix = "eclipse.uss.app-tokens-filter")
+public interface ApplicationTokenFilterConfig {
+
+    @WithDefault(value = "true")
+    boolean enabled();
+
+    Map<String, String> allowedTokens();
+}