Evaluate TypeRegistry as a runtime instance

3 big changes seem to be required here:
- injecting the type registry in the Connection
- injecting the type registry in the Platform
- Dealing with Table::addColumn

Possible steps for the 2 first items:
- have a type registry in the configuration
- use it when instantiating the driver in DriverManager
- the driver can then instantiate the platform with the type registry
- the driver can provide the type registry to Connection

src/Connection.php

@@ -1596,6 +1596,8 @@ public function isRollbackOnly()
      */
     public function convertToDatabaseValue($value, $type)
     {
+        // Either we deprecate this method, or we add the type registry as a
+        // dependency
         return Type::getType($type)->convertToDatabaseValue($value, $this->getDatabasePlatform());
     }
 
@@ -1612,6 +1614,7 @@ public function convertToDatabaseValue($value, $type)
      */
     public function convertToPHPValue($value, $type)
     {
+        // same as above
         return Type::getType($type)->convertToPHPValue($value, $this->getDatabasePlatform());
     }
 
@@ -1669,6 +1672,7 @@ private function _bindTypedValues(DriverStatement $stmt, array $params, array $t
     private function getBindingInfo($value, $type): array
     {
         if (is_string($type)) {
+            // same as above
             $type = Type::getType($type);
         }
 

src/Platforms/AbstractPlatform.php

@@ -174,6 +174,7 @@ private function initializeAllDoctrineTypeMappings(): void
     {
         $this->initializeDoctrineTypeMappings();
 
+        // the platform will also need to know about the type registry
         foreach (Type::getTypesMap() as $typeName => $className) {
             foreach (Type::getType($typeName)->getMappedDatabaseTypes($this) as $dbType) {
                 $this->doctrineTypeMapping[$dbType] = $typeName;

src/Schema/DB2SchemaManager.php

@@ -120,6 +120,8 @@ protected function _getPortableTableColumnDefinition($tableColumn)
             $options['precision'] = $precision;
         }
 
+        // most schema managers perform that kind of call. They know about both
+        // the connection and the platform
         return new Column($tableColumn['colname'], Type::getType($type), $options);
     }
 

src/Schema/Table.php

@@ -348,6 +348,8 @@ private function _createIndex(
      */
     public function addColumn($name, $typeName, array $options = [])
     {
+        // either the signature of addColumn should require a Type instance, or
+        // we should pass a string to Column::__construct and resolve the type later on
         $column = new Column($name, Type::getType($typeName), $options);
 
         $this->_addColumn($column);

src/Statement.php

@@ -100,6 +100,7 @@ public function bindValue($param, $value, $type = ParameterType::STRING)
 
         if ($type !== null) {
             if (is_string($type)) {
+                // The type registry could be obtained from the connection
                 $type = Type::getType($type);
             }
 

src/Types/Type.php

@@ -153,7 +153,7 @@ public static function getType($name)
      *
      * @throws Exception
      */
-    public static function addType($name, $className)
+    public static function addType($name, $className) // this method is only ever used in tests
     {
         self::getTypeRegistry()->register($name, new $className());
     }
@@ -165,7 +165,7 @@ public static function addType($name, $className)
      *
      * @return bool TRUE if type is supported; FALSE otherwise.
      */
-    public static function hasType($name)
+    public static function hasType($name) // used once in AbstractPlatform
     {
         return self::getTypeRegistry()->has($name);
     }
@@ -180,7 +180,7 @@ public static function hasType($name)
      *
      * @throws Exception
      */
-    public static function overrideType($name, $className)
+    public static function overrideType($name, $className) // used exclusively in tests
     {
         self::getTypeRegistry()->override($name, new $className());
     }
@@ -204,7 +204,7 @@ public function getBindingType()
      *
      * @return string[]
      */
-    public static function getTypesMap()
+    public static function getTypesMap() // used in AbstractPlatform
     {
         return array_map(
             static function (Type $type): string {