Proposal (4.0): Inline global preparations into actions at compile time

**Is your feature request related to a problem? Please describe.**

We ran into an issue where we were loading data in a preparation for a default read action, which caused other issues, but we weren't getting the new warning advising not to do that (introduced in e5656b6cc2b191dd26d6ab96b5563fbe1fcaa5fe).

The reason is because the preparation was a global one, ie. in a `preparations` block, not in a specific action. These preparations aren't inlined into the action at compile time, meaning calling `Ash.Resource.Info.action(MyResource, :read)` won't list the preparation even though it will apply.

**Describe the solution you'd like**

These preparations should be added to each of the actions they apply to, at compile time. For now this will be all actions, as preparations can't have conditions, but later on conditions may be added.

Start by tracing how global preparations are represented and how actions are compiled, then compare that with what Ash.Resource.Info.action(MyResource, :read) exposes. Done means preparations from a preparations block appear on every applicable action at compile time, while preserving the stated future possibility of conditional preparations.

Written by the indexing model from the issue text.