feat: Enhance PostgreSQL type handling and migration scripts

- Introduced equivalent base types and variants for PostgreSQL types to normalize type comparisons.
- Added functions for normalizing SQL types and retrieving equivalent type variants.
- Updated migration writer to handle type alterations with checks for existing types.
- Implemented logic to create necessary extensions (e.g., pg_trgm) based on schema requirements.
- Enhanced tests to cover new functionality for type normalization and migration handling.
- Improved handling of GIN indexes to use appropriate operator classes based on column types.

pkg/writers/pgsql/templates.go

@@ -95,6 +95,16 @@ type AlterColumnTypeData struct {
 	TableName  string
 	ColumnName string
 	NewType    string
+	UsingExpr  string
+}
+
+type AlterColumnTypeWithCheckData struct {
+	SchemaName      string
+	TableName       string
+	ColumnName      string
+	NewType         string
+	EquivalentTypes string
+	UsingExpr       string
 }
 
 // AlterColumnDefaultData contains data for alter column default template
@@ -302,6 +312,15 @@ func (te *TemplateExecutor) ExecuteAlterColumnType(data AlterColumnTypeData) (st
 	return buf.String(), nil
 }
 
+func (te *TemplateExecutor) ExecuteAlterColumnTypeWithCheck(data AlterColumnTypeWithCheckData) (string, error) {
+	var buf bytes.Buffer
+	err := te.templates.ExecuteTemplate(&buf, "alter_column_type_with_check.tmpl", data)
+	if err != nil {
+		return "", fmt.Errorf("failed to execute alter_column_type_with_check template: %w", err)
+	}
+	return buf.String(), nil
+}
+
 // ExecuteAlterColumnDefault executes the alter column default template
 func (te *TemplateExecutor) ExecuteAlterColumnDefault(data AlterColumnDefaultData) (string, error) {
 	var buf bytes.Buffer