Rename to uv (#1302)

First, replace all usages in files in-place. I used my editor for this.
If someone wants to add a one-liner that'd be fun.

Then, update directory and file names:

```
# Run twice for nested directories
find . -type d -print0 | xargs -0 rename s/puffin/uv/g
find . -type d -print0 | xargs -0 rename s/puffin/uv/g

# Update files
find . -type f -print0 | xargs -0 rename s/puffin/uv/g
```

Then add all the files again

```
# Add all the files again
git add crates
git add python/uv

# This one needs a force-add
git add -f crates/uv-trampoline
```

crates/uv-resolver/src/resolver/index.rs

@@ -0,0 +1,25 @@
+use dashmap::DashMap;
+use url::Url;
+
+use distribution_types::PackageId;
+use once_map::OnceMap;
+use pypi_types::Metadata21;
+use uv_normalize::PackageName;
+
+use super::provider::VersionsResponse;
+
+/// In-memory index of package metadata.
+#[derive(Default)]
+pub struct InMemoryIndex {
+    /// A map from package name to the metadata for that package and the index where the metadata
+    /// came from.
+    pub(crate) packages: OnceMap<PackageName, VersionsResponse>,
+
+    /// A map from package ID to metadata for that distribution.
+    pub(crate) distributions: OnceMap<PackageId, Metadata21>,
+
+    /// A map from source URL to precise URL. For example, the source URL
+    /// `git+https://github.com/pallets/flask.git` could be redirected to
+    /// `git+https://github.com/pallets/flask.git@c2f65dd1cfff0672b902fd5b30815f0b4137214c`.
+    pub(crate) redirects: DashMap<Url, Url>,
+}