Add convenience method setAttribute(Attribute<Long>, int) to SpanBuilder (matching the existing convenience method in Span)

[trask]

It would be nice if SpanBuilder had the same setAttribute(AttributeKey<Long> key, int value) convenience method as Span:

opentelemetry-java/api/all/src/main/java/io/opentelemetry/api/trace/Span.java

Lines 169 to 171 in 6c0d140

	default Span setAttribute(AttributeKey<Long> key, int value) {
	return setAttribute(key, (long) value);
	}

[Stoyas]

trying to work on it