Introduce system APIs for VibrationEffect XML parser

Introduce SystemApi for VibrationEffect XML parser:

- VibrationXmlParser.parse
- VibrationXmlParser.parseVibrationEffect
- ParsedVibration.resolve

Update CTS tests to only use the new methods and remove TestApi from
other hidden helpers. The tests are not flagged since they are required
to ensure OEMs will preserve the XML schema defined at

core/xsd/schema/vibrator/vibration/vibration.xsd

Bug: 347273158
Test: atest android.os.cts.VibrationEffectXmlSerializationTest
      atest android.os.vibrator.persistence
Flag: android.os.vibrator.vibration_xml_apis
Change-Id: Ida2d4a518fc6ce7dc15f26680ca970df26ce530f