Move architecture and operating system probing to Python (#2381)

The architecture of uv does not necessarily match that of the python
interpreter (#2326). In cross compiling/testing scenarios the operating
system can also mismatch. To solve this, we move arch and os detection
to python, vendoring the relevant pypa/packaging code, preventing
mismatches between what the python interpreter was compiled for and what
uv was compiled for.

To make the scripts more manageable, they are now a directory in a
tempdir and we run them with `python -m` . I've simplified the
pypa/packaging code since we're still building the tags in rust. A
`Platform` is now instantiated by querying the python interpreter for
its platform. The pypa/packaging files are copied verbatim for easier
updates except a `lru_cache()` python 3.7 backport.

Error handling is done by a `"result": "success|error"` field that allow
passing error details to rust:

```console
$ uv venv --no-cache
  × Can't use Python at `/home/konsti/projects/uv/.venv/bin/python3`
  ╰─▶ Unknown operation system `linux`
```

I've used the [maturin sysconfig
collection](https://github.com/PyO3/maturin/tree/855f6d2cb1fb8fb43c2bb9e500ab0e5e84bd3140/sysconfig)
as reference. I'm unsure how to test these changes across the wide
variety of platforms.

Fixes #2326

crates/uv-dev/src/resolve_cli.rs

@@ -11,7 +11,6 @@ use petgraph::dot::{Config as DotConfig, Dot};
 
 use distribution_types::{FlatIndexLocation, IndexLocations, IndexUrl, Resolution};
 use pep508_rs::Requirement;
-use platform_host::Platform;
 use uv_cache::{Cache, CacheArgs};
 use uv_client::{FlatIndex, FlatIndexClient, RegistryClientBuilder};
 use uv_dispatch::BuildDispatch;
@@ -54,8 +53,7 @@ pub(crate) struct ResolveCliArgs {
 pub(crate) async fn resolve_cli(args: ResolveCliArgs) -> Result<()> {
     let cache = Cache::try_from(args.cache_args)?;
 
-    let platform = Platform::current()?;
-    let venv = PythonEnvironment::from_virtualenv(platform, &cache)?;
+    let venv = PythonEnvironment::from_virtualenv(&cache)?;
     let index_locations =
         IndexLocations::new(args.index_url, args.extra_index_url, args.find_links, false);
     let client = RegistryClientBuilder::new(cache.clone())