Replace CRM_Core_DAO_Base with (mostly) static alias CRM_*_DAO_Base

* This approach defines `CRM_*_DAO_Base`.

* When deployed on 5.74+, `CRM_*_DAO_Base` will be exactly the same as `CRM_Core_DAO_Base`
  In other words:

    class CRM_Foo_DAO_MyData extends CRM_Foo_DAO_Base {}
    class_alias('CRM_Core_DAO_Base', 'CRM_Foo_DAO_Base');
    class CRM_Core_DAO_Base extends CRM_Core_DAO {}

* When deployed on <5.74, `CRM_*_DAO_Base` will use the anonymous backport
  variant from civimix. In other words:

    class CRM_Foo_DAO_MyData extends CRM_Foo_DAO_Base {}
    class_alias('CiviMix\Schema\Foo\DAO', 'CRM_Foo_DAO_Base');
    ^^ Read anonymous class... which extends CRM_Core_DAO

* In this arrangement, the anonymous DAO implementation is -only- used on
  old versions. Once you get to 5.74+, you use the local base. This should
  provide better IDE hints and simpler callstacks. You presumptively do not
  get backports of changes/improvements in the DAO base.

src/CRM/CivixBundle/Resources/views/Code/entity-dao.php.php

@@ -13,6 +13,9 @@
  * This stub provides compatibility. It is not intended to be modified in a
  * substantive way. However, you may add comments and annotations.
  */
-class <?php echo $daoClassName ?> extends CRM_Core_DAO_Base {
+class <?php echo $daoClassName ?> extends <?php echo $_namespace . '_DAO_Base'; ?> {
+
+  // Required by some versions of CiviCRM.
+  public static $_tableName = <?php var_export($tableName); ?>;
 
 }

src/CRM/CivixBundle/Resources/views/Code/module.civix.php.php

@@ -104,8 +104,22 @@ public static function schema() {
 spl_autoload_register('_<?php echo $mainFile ?>_civix_class_loader', TRUE, TRUE);
 
 function _<?php echo $mainFile ?>_civix_class_loader($class) {
-  // This allows us to tap-in to the installation process (without incurring real file-reads on typical requests).
 <?php $_clPrefix = 'CiviMix\\Schema\\' . \CRM\CivixBundle\Utils\Naming::createCamelName($mainFile) . '\\' ?>
+<?php $_localBase = $_namespace . '_DAO_Base'; ?>
+  if ($class === <?php var_export($_localBase); ?>) {
+    if (version_compare(CRM_Utils_System::version(), '5.74.beta', '>=')) {
+      class_alias('CRM_Core_DAO_Base', <?php var_export($_localBase); ?>);
+      // ^^ Materialize concrete names -- encourage IDE's to pick up on this association.
+    }
+    else {
+      $realClass = <?php var_export($_clPrefix . "DAO") ?>;
+      class_alias($realClass, $class);
+      // ^^ Abstract names -- discourage IDE's from picking up on this association.
+    }
+    return;
+  }
+
+  // This allows us to tap-in to the installation process (without incurring real file-reads on typical requests).
   if (strpos($class, <?php var_export($_clPrefix) ?>) === 0) {
     // civimix-schema@5 is designed for backported use in download/activation workflows,
     // where new revisions may become dynamically available.