Improve Resource related public APIs

[utpilla]

Resource related public APIs need some improvement:

1. Remove the timeout parameter from the detect method signature of the trait ResourceDetector. This doesn't seem to add any value. The individual resource detectors implementing this trait can account for timeout in their implementation if required.
2. Use a builder pattern for creating resource to make it simpler for users to add custom detectors. Currently, this functionality is offered by from_detectors method.