Allowing to log SObject without ID field

[TrangOul]

Fixes #911 . Skips saving the ID of the record if it doesn’t have one.

The try approach seems to run about ≈ 40×-50× faster than querying the Schema:

if (record.getSObjectType().getDescribe().fields.getMap().containsKey('Id')) {
	this.logEntryEvent.RecordId__c = record.Id
}

and ≈ 6×-7× faster than cached version of the Schema:

private static final Map<String, Boolean> CACHED_SOBJECT_NAME_TO_HAS_ID_FIELD = new Map<String, Boolean>();
private static Boolean getHasIdField(Schema.SObjectType sobjectType) {
	final String sobjectName = sobjectType.toString();
	if (CACHED_SOBJECT_NAME_TO_HAS_ID_FIELD.containsKey(sobjectName)) {
		return CACHED_SOBJECT_NAME_TO_HAS_ID_FIELD.get(sobjectName);
	}
	final Boolean hasIdField = sobjectType.getDescribe().fields.getMap().containsKey('Id');
	CACHED_SOBJECT_NAME_TO_HAS_ID_FIELD.put(sobjectName, hasIdField);
	return hasIdField;
}

(...)

if (this.getHasIdField(record.getSObjectType())) {
	this.logEntryEvent.RecordId__c = record.Id
}