Add Pydantic model for `details` field in HTTP Exceptions

[slangeveld]

Some of the HTTP Exceptions raised by fmu-seetings-api passes a dictionary in the details field in order to send different types of data back to the GUI, e.g.

fmu-settings-api/src/fmu_settings_api/v1/routes/project.py

Lines 205 to 209 in 657c03a

	detail={
	"message": "The global config file is not valid at path "
	f"{global_config_path}.",
	"validation_errors": e.errors(),
	},

Make this details field a Pydantic model.

[GibranAlfa]

is this still relevant?