Building an AMX CI

I'm trying to build an AMX CI on our fork: https://github.com/libxsmm/aster

These are the two loops:
* [Rebase](https://github.com/libxsmm/aster/actions/workflows/pull-rebase.yml)
* [AMX test](https://github.com/libxsmm/aster/actions/workflows/intel-amx.yml)

This is a copy of what [we did](https://github.com/libxsmm/lighthouse/tree/main/.github/workflows) in Lighthouse.

The idea is to run the rebase every night and the AMX tests every time the `main` branch changes. Even if we would one day use this fork for development, we'd contribute with `local branch` -> `aster/main` -> `xsmm/main`, so that `main` branch still only updates when there are new commits in `aster/main`.

The main questions I have are:
1. What's the simplest way to build LLVM without [relying on docker](https://github.com/iree-org/aster/tree/main/tools/pkgs/llvm)?
2. What's the minimum set of dependencies (packages, libs) that I need to just run the AMX code?
3. What are the required CMake flags I need to set to build and run the AMX tests only?

@nicolasvasilache