feat: add environment variable to disable writing installer metadata files (#8877)
## Summary
This change introduces the `UV_NO_INSTALLER_METADATA` environment
variable
as a way to opt out of the extra installer metadata files that `uv` is
creating.
This is important to achieve reproducible builds in distribution
packaging, allowing to replace usage of
[installer](https://pypi.org/project/installer) with `uv pip install`.
At the time of writing these files are:
- `uv_cache.json`
Contains timestamps which are non-reproducible.
These hashes also leak in to the `RECORD` file.
- `direct_url.json`
Contains the path to the installed wheel.
While not non-reproducible it's not required for distribution packaging.
- `INSTALLER`
Again, not non-reproducible, but of no value in distribution packaging.
## Test Plan
Automated test added.
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Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>