Add read only database configuration/builder option

When using DatabaseBuilder.readOnlyDatabase(true) then
ebean will:
- Set the DataSourceBuilder to use autoCommit=true and readOnly=true
- Use the same DataSource instance for both dataSource and readOnlyDataSource

This is to simplify the setup/configuration for creating a Database that
will only have read-only use.

Note that readOnly=true is a JDBC hint and for example H2 database effectively
ignores that hint where as Postgres will enforce the read-only true nature.

ebean-api/src/main/java/io/ebean/DatabaseBuilder.java

@@ -1053,6 +1053,14 @@ public interface DatabaseBuilder {
   @Deprecated
   DatabaseBuilder setSkipDataSourceCheck(boolean skipDataSourceCheck);
 
+  /**
+   * Set to true if this database is used in a read only way.
+   * <p>
+   * The DataSource and read-only DataSource are expected to be the same
+   * and use readOnly=true and autoCommit=true.
+   */
+  DatabaseBuilder readOnlyDatabase(boolean readOnlyDatabase);
+
   /**
    * Set a DataSource.
    */
@@ -2607,6 +2615,14 @@ public interface DatabaseBuilder {
      */
     boolean skipDataSourceCheck();
 
+    /**
+     * Return true if this database is used in a read only way.
+     * <p>
+     * The DataSource and read-only DataSource are expected to be the same
+     * and use readOnly=true and autoCommit=true.
+     */
+    boolean readOnlyDatabase();
+
     /**
      * Return the DataSource.
      */

ebean-api/src/main/java/io/ebean/config/DatabaseConfig.java

@@ -304,6 +304,8 @@ public class DatabaseConfig implements DatabaseBuilder.Settings {
 
   private boolean skipDataSourceCheck;
 
+  private boolean readOnlyDatabase;
+
   /**
    * The data source (if programmatically provided).
    */
@@ -1343,6 +1345,17 @@ public class DatabaseConfig implements DatabaseBuilder.Settings {
     return this;
   }
 
+  @Override
+  public DatabaseBuilder readOnlyDatabase(boolean readOnlyDatabase) {
+    this.readOnlyDatabase = readOnlyDatabase;
+    return this;
+  }
+
+  @Override
+  public boolean readOnlyDatabase() {
+    return readOnlyDatabase;
+  }
+
   @Override
   public DataSource getDataSource() {
     return dataSource;