Resolves #119.

Resource detection is currently naive:

• We only have the ability to specify an allow list / disallow list of attributes that come from resource detectors.
• Its assumed / implied that all resource detectors are enabled, which conflicts with declarative config's "what you see is what you get" philosophy.
• There is no ability to pass configuration to a particular resource detector.
• There is no ability to influence the order of resource detectors, so if two provide the same attribute, you're at the mercy of whatever order they were applied in.

This PR refactors resource detection to add more expressiveness and better accommodate a wide range of use cases.

Let's take a look at an example config after this refactor:

resource:
  attributes:
    - name: service.name
       value: my-service
  detection/development:
    detectors:
      - container:
      - os:
      - host:
      - process:
    attributes:
      excluded:
        - process.command_line

Most users will want to set a static set of resource attributes, especially service.*, but resource detection is an important part of the otel ecosystem. You opt into resource detection by setting resource.detection/development and configuring to suit.

.detectors is an array of objects, each with a single key referring to the name of a detector, and an object value passed to that detector to optionally configure it. This aligns resource detectors which the design of other SDK extension components.

The ability to include / exclude attributes provided by the collection of all resource detectors is still available.