Support async reconciliation

### What problem are you facing?

For some time, upjet-based providers have been reconciling resources asynchronously. In order to do so, it "lies" to managed reconciler. Doing so causes lots of issues. So far, we have discussed the topic under those issues. It would be better if we could track them here, in a single place.

- https://github.com/crossplane/crossplane/issues/5918 see this [comment](https://github.com/crossplane/crossplane/issues/5918#issuecomment-2348094947)
- https://github.com/crossplane/upjet/issues/439 see this [comment](https://github.com/crossplane/upjet/issues/439#issuecomment-2383569412)
- https://github.com/crossplane-contrib/provider-upjet-azure/issues/802
- https://github.com/crossplane-contrib/provider-upjet-aws/issues/1715

### How could Crossplane help solve your problem?

Support async reconciliation in [managed reconciler](https://github.com/crossplane/crossplane-runtime/blob/main/pkg/reconciler/managed/reconciler.go).

Start with pkg/reconciler/managed/reconciler.go and read the linked discussions in Crossplane issue 5918 and Upjet issue 439, along with the provider issues listed here. Clarify the async reconciliation requirements and design before making changes; done means managed reconciler support is defined and the reported provider scenarios no longer require it to be misled.

Written by the indexing model from the issue text.