PhoneConfigurationManager: query vDSDA capability

- PCM will query resource overlay for config_enable_virtual_dsda
to determine if static capability for 'max active voice subscriptions'
needs to be updated.

Bug: 249857869
Test: PhoneConfigurationManagerTest#testConfigureAndGetMaxActiveVoiceSubscriptions()
Change-Id: Iffbfafdbc28cba1aec64d4e5d6897968cfd621f6