Add capability to use multi source DB connection for prim/sec or r/w conns

Switched to provider to enable runtime switching capability of Persistence DAO without having to recompile the common package. Added config interface, though there seems to be an issue in loading it in the implementing app.

core/src/main/java/org/eclipsefoundation/core/namespace/MicroprofilePropertyNames.java

@@ -9,6 +9,7 @@ package org.eclipsefoundation.core.namespace;
 public class MicroprofilePropertyNames {
 	public static final String CACHE_TTL_MAX_SECONDS = "cache.ttl.write.seconds";
 	public static final String CACHE_SIZE_MAX = "cache.max.size";
+    public static final String MULTI_SOURCE_SINGLE_TENANT_ENABLED = "eclipse.persistence.msst.enabled";
 	public static final String DEFAULT_PAGE_SIZE = "eclipse.pagination.page-size.default";
 	public static final String DISTRIBUTED_CSRF_MODE = "security.csrf.enabled.distributed-mode";