Update constructor to follow CasC best practices (#406)

* move non-required values into databound setters and create validations

* create default value constants for primitives of FleetClouds and clean up getters

* create new constructors with CasC best practices

* fix CasC unit tests

* update casc docs to reflect new defaults, add unlisted fields to examples, and include EC2FleetLabelCloud examples

* change default minSize to 0 in jelly for consistency

Author: vineeth-bandi

docs/CONFIGURATION-AS-CODE.md

@@ -0,0 +1,33 @@
+package com.amazon.jenkins.ec2fleet;
+
+class CloudConstants {
+
+    static final String EC2_INSTANCE_TAG_NAMESPACE = "ec2-fleet-plugin";
+    static final String EC2_INSTANCE_CLOUD_NAME_TAG = EC2_INSTANCE_TAG_NAMESPACE + ":cloud-name";
+    static final boolean DEFAULT_PRIVATE_IP_USED = false;
+
+    static final boolean DEFAULT_ALWAYS_RECONNECT = false;
+
+    static final int DEFAULT_IDLE_MINUTES = 0;
+
+    static final int DEFAULT_MIN_SIZE = 0;
+
+    static final int DEFAULT_MAX_SIZE = 1;
+
+    static final int DEFAULT_MIN_SPARE_SIZE = 0;
+
+    static final int DEFAULT_NUM_EXECUTORS = 1;
+
+    static final boolean DEFAULT_ADD_NODE_ONLY_IF_RUNNING = false;
+
+    static final boolean DEFAULT_RESTRICT_USAGE = false;
+
+    static final boolean DEFAULT_SCALE_EXECUTORS_BY_WEIGHT = false;
+
+    static final int DEFAULT_CLOUD_STATUS_INTERVAL_SEC = 10;
+
+    static final int DEFAULT_INIT_ONLINE_TIMEOUT_SEC = 3 * 60;
+    static final int DEFAULT_INIT_ONLINE_CHECK_INTERVAL_SEC = 15;
+
+    static final int DEFAULT_MAX_TOTAL_USES = -1;
+}