Refactor autoconfigure to implement exporter provider SPIs

[jack-berg]

Discussed in this comment.

Autoconfigure currently has compileOnly dependencies the exporter modules, along with a bunch of exporter-specific configuration to extract the relevant properties ConfigProperties and configure exporters. It makes autoconfigure pretty cumbersome to maintain, since there are test suites verifying the configured behavior of different exporters.

It would be better for maintainability and separation of concerns if the tests and the configuration code where decentralized and lived in the exporter modules. The stability of :sdk:autoconfigure-spi makes this straight forward to implement.