Incorporating #8637 into #8458
- Adds `python-managed` feature selection to Windows CI for `python
install` tests
- Adds trampoline sniffing utilities to `uv-trampoline-builder`
- Uses a trampoline to install Python executables into the `PATH` on
Windows
Currently, our trampoline is used to convert `<command> [args]` to
`python <command> [args]` for script entrypoints installed into virtual
environments. For #8458, it'd be nice to convert a shim `python3.12
[args]` to `python [args]`. Here, we modify the trampolines to support
this use-case.
The only change we really need here is to avoid injecting `<command>`
into the child process. We change the "magic number" at the end of the
trampoline executables from `UVUV` to `UVSC` and `UVPY` which define
"script" and "python" variants to the trampoline. We then omit the
`<command>` injection in the latter case. We also omit writing the zip
script payload.
To support construction of the new variant, a new
`uv-trampoline-builder` crate is introduced — this avoids requirements
on `uv-install-wheel` in future work. I also use `uv-trampoline-builder`
to consolidate some of the test setup for `uv-trampoline`.
There should be no backwards compatibility concerns, since trampolines
are fully self-referential.
I rebased to fix the commits at the end, as this took many iterations to
get working via CI. This should roughly be reviewable by commit if you
prefer.
