Are `fast_length()` and `fast_normalize()` deprecated?

### Specification Version

SYCL Next (Source)

### Section Number(s)

Also in SYCL 2020:

* [`fast_length()`](https://registry.khronos.org/SYCL/specs/sycl-2020/html/sycl-2020.html#api:fast_length)
* [`fast_normalize()`](https://registry.khronos.org/SYCL/specs/sycl-2020/html/sycl-2020.html#api:fast_normalize)

### Issue Description

#833 deprecated the `sycl::half_precision::` namespace. `fast_length()` and `fast_normalize()` are in the `sycl::` namespace, but are specified in terms of `half_precision` square roots. Either `fast_length()` and `fast_normalize()` need to be redefined without reference to `half_precision`, or they need to also be deprecated.

### Code Example (Optional)

_No response_

Start with the linked SYCL 2020 sections for fast_length() and fast_normalize(), then review issue #833 on the deprecated sycl::half_precision namespace. Determine whether these functions should be redefined without half_precision or also deprecated; the specification is done when this ambiguity is resolved and the relevant wording is updated.

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