Add UV_UPLOAD_HTTP_TIMEOUT and respect UV_HTTP_TIMEOUT in uploads (#16040)

## Summary
- Move parsing `UV_HTTP_TIMEOUT`, `UV_REQUEST_TIMEOUT` and
`HTTP_TIMEOUT` to `EnvironmentOptions`
- Add new env varialbe `UV_UPLOAD_HTTP_TIMEOUT`

Relates https://github.com/astral-sh/uv/issues/14720

## Test Plan

Tests with existing tests

docs/reference/environment.md

@@ -651,6 +651,10 @@ Equivalent to the `--torch-backend` command-line argument (e.g., `cpu`, `cu126`,
 Used ephemeral environments like CI to install uv to a specific path while preventing
 the installer from modifying shell profiles or environment variables.
 
+### `UV_UPLOAD_HTTP_TIMEOUT`
+
+Timeout (in seconds) for only upload HTTP requests. (default: 900 s)
+
 ### `UV_VENV_CLEAR`
 <small class="added-in">added in `0.8.0`</small>