chore: no longer convert in relative unix path constructor (#5552)

### Description

To quote @gsoltis:
> In general:
> - constructors should validate, to the extent they can (not much for
`unix` paths, but can verify relative)
> - conversions should be explicit. You need to know where you're
starting from. If this were an AnchoredSystemPath on windows, the `\` ->
`/` makes sense. If it's a literal from e.g. a tar file, then it
doesn't.

Reviewers Notes:
- Opening up this PR in VSCode and using `Find All References` on the
constructor is useful for double checking that I didn't miss a
conversion.
- Clippy error appeared on local when I made these changes. Fixed it
just in case that would block CI
- Moved `to_unix` to `AnchoredSystemPath` instead of
`AnchoredSystemPathBuf` now that we have deref coercion which will
automatically convert `&AnchroedSystemPathBuf` to `&AnchoredSystemPath`
and moving the method allows it to be called from either type.

### Testing Instructions

Looked through all uses of `RelativeUnixPathBuf::new` to see if there
were places that depended on the conversion. The only use that was
obvious was the usage in `cache_archive/create.rs`. `dotEnv` was the
only other place where we possibly were converting a system path to a
relative unix. We don't specify that `dotEnv` entries should be unix
relative, so we might've been accidentally supporting system paths, but

---------

Co-authored-by: Chris Olszewski <Chris Olszewski>

crates/turborepo-cache/src/cache_archive/create.rs

@@ -83,7 +83,7 @@ impl<'a> CacheWriter<'a> {
         let file_info = source_path.symlink_metadata()?;
 
         // Normalize the path within the cache
-        let mut file_path = RelativeUnixPathBuf::new(file_path.as_str())?;
+        let mut file_path = file_path.to_unix()?;
         file_path.make_canonical_for_tar(file_info.is_dir());
 
         let mut header = Self::create_header(&source_path, &file_info)?;

crates/turborepo-paths/src/anchored_system_path.rs

@@ -2,7 +2,7 @@ use std::{fmt, path::Path};
 
 use camino::{Utf8Component, Utf8Path};
 
-use crate::{AnchoredSystemPathBuf, PathError};
+use crate::{AnchoredSystemPathBuf, PathError, RelativeUnixPathBuf};
 
 pub struct AnchoredSystemPath(Utf8Path);
 
@@ -71,4 +71,17 @@ impl AnchoredSystemPath {
     pub fn as_path(&self) -> &Path {
         self.0.as_std_path()
     }
+
+    pub fn to_unix(&self) -> Result<RelativeUnixPathBuf, PathError> {
+        #[cfg(unix)]
+        {
+            return RelativeUnixPathBuf::new(self.0.as_str());
+        }
+        #[cfg(not(unix))]
+        {
+            use crate::IntoUnix;
+            let unix_buf = self.0.into_unix();
+            RelativeUnixPathBuf::new(unix_buf)
+        }
+    }
 }

crates/turborepo-paths/src/anchored_system_path_buf.rs

@@ -8,10 +8,7 @@ use std::{
 use camino::{Utf8Component, Utf8Components, Utf8Path, Utf8PathBuf};
 use serde::{Deserialize, Serialize};
 
-use crate::{
-    check_path, AbsoluteSystemPath, AnchoredSystemPath, PathError, PathValidation,
-    RelativeUnixPathBuf,
-};
+use crate::{check_path, AbsoluteSystemPath, AnchoredSystemPath, PathError, PathValidation};
 
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Default, Serialize, Deserialize)]
 pub struct AnchoredSystemPathBuf(pub(crate) Utf8PathBuf);
@@ -192,19 +189,6 @@ impl AnchoredSystemPathBuf {
         self.0.as_std_path()
     }
 
-    pub fn to_unix(&self) -> Result<RelativeUnixPathBuf, PathError> {
-        #[cfg(unix)]
-        {
-            return RelativeUnixPathBuf::new(self.0.as_str());
-        }
-        #[cfg(not(unix))]
-        {
-            use crate::IntoUnix;
-            let unix_buf = self.0.as_path().into_unix();
-            RelativeUnixPathBuf::new(unix_buf)
-        }
-    }
-
     pub fn push(&mut self, path: impl AsRef<Utf8Path>) {
         self.0.push(path.as_ref());
     }

crates/turborepo-paths/src/relative_unix_path_buf.rs

@@ -8,7 +8,7 @@ use std::{
 use camino::Utf8Path;
 use serde::Serialize;
 
-use crate::{IntoUnix, PathError, RelativeUnixPath};
+use crate::{PathError, RelativeUnixPath};
 
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Default, Serialize)]
 #[serde(transparent)]
@@ -27,9 +27,7 @@ impl RelativeUnixPathBuf {
             return Err(PathError::NotRelative(path_string));
         }
 
-        let unix_path = path_string.into_unix();
-
-        Ok(Self(unix_path.into()))
+        Ok(Self(path_string))
     }
 
     pub fn into_inner(self) -> String {

crates/turborepo-scm/src/ls_tree.rs

@@ -103,6 +103,8 @@ mod tests {
                 &[("package.json", "e69de29bb2d1d6434b8b29ae775ad8c2e48c5391")],
             ),
             (
+                // We aren't attempting to use octal escapes here, it just looks like it
+                #[allow(clippy::octal_escapes)]
                 "100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391\t\t\000100644 blob \
                  e69de29bb2d1d6434b8b29ae775ad8c2e48c5391\t\"\000100644 blob \
                  5b999efa470b056e329b4c23a73904e0794bdc2f\t\n\000100644 blob \