Auto merge of #131044 - EnzymeAD:enzyme-testinfra, r=jieyouxu

add has_enzyme/needs-enzyme to the test infra

This unblocks merging the Enzyme / Autodiff frontend.
For the full implementation, see: rust-lang/rust#129175

We don't want to run tests that require Enzyme / Autodiff support when we build rustc without the required features.

It correctly filtered out a test which started with `//@ needs-enzyme`.
```
running 80 tests
i...............................................................................

test result: ok. 79 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out; finished in 380.41ms
```

Tracking:

- rust-lang/rust#124509

r? jieyouxu

Author: bors