PubSub DSL module option doesn't expand aliases.

**Describe the bug**
Specifying an alias as the module for a pub sub fails with:

```
** (UndefinedFunctionError) function PubSub.broadcast/3 is undefined (module PubSub is not available). Did you mean:

* MyApp.PubSub.broadcast/3
```

**To Reproduce**
```elixir
alias MyApp.PubSub

pub_sub do
module PubSub
end
```

**Expected behavior**
It publishes pubsub messages.

**Runtime**
- Elixir version: `1.16.3`
- Erlang version: `27.0`
- OS: `Darwin Eeloo 23.5.0 Darwin Kernel Version 23.5.0: Wed May 1 20:12:58 PDT 2024; root:xnu-10063.121.3~5/RELEASE_ARM64_T6000 arm64`
- Ash version: `3.0.2`
- any related extension versions

**Additional context**
Add any other context about the problem here.

Start by tracing the pub_sub DSL's module option using the alias-based reproduction in the issue, then check how the configured module is resolved before broadcasting. Done means the aliased MyApp.PubSub module publishes pubsub messages without the UndefinedFunctionError.

Written by the indexing model from the issue text.