[BCF] New BCF XML handler with better performances (#2355)

BREAKING CHANGE: incompatible methods and objects with previous version.

closes #2321

src/bcf/tests/conftest.py

@@ -0,0 +1,8 @@
+import pytest
+
+from bcf.xml_parser import XmlParserSerializer
+
+
+@pytest.fixture(scope="session")
+def xml_handler() -> XmlParserSerializer:
+    return XmlParserSerializer()