Add an sdf::ParserConfig object to ServerConfig

[scpeters]

Desired behavior

Currently the gz::sim::Server constructor creates an sdf::ParserConfig object from sdf::ParserConfig::GlobalConfig() and uses it to configure the parsing behavior when loading the world from an SDFormat string or file.

There are other SDFormat parsing configurations that a user might like to set. Adding an sdf::ParserConfig object to ServerConfig would allow users who programmatically instantiate a gz::sim::Server to configure this behavior.

Alternatives considered

Implementation suggestion

Additional context