Use correct seperation in each place needed when loading LFS (#837)

https://github.com/actions/toolkit/blob/d70fb49aaa0517f8c92e4e2e9406c8a5414f3fec/packages/glob/src/glob.ts#L11
indicated that newlines were supported, and it worked

It requires a few hacks, but I think this is a more robust long-term state

.github/workflows/ci.yml

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bb46196..5f70ccd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -15,8 +15,8 @@
   # List of packages that can not target Wasm.
   # `vello_tests` uses `nv-flip`, which doesn't support Wasm.
   NO_WASM_PKGS: "--exclude vello_tests --exclude simple_sdl2"
-  # The files stored in LFS the tests need to access
-  LFS_FILES: "vello_tests/snapshots/*.png,sparse_strips/vello_cpu/refs/*.png"
+  # The files stored in LFS the tests need to access, in JSON format
+  LFS_FILES: '["vello_tests/snapshots/*.png", "sparse_strips/vello_cpu/refs/*.png"]'
 
 
 # Rationale
@@ -168,7 +168,8 @@
 
     - id: calc-hash
       name: Calculate LFS hash
-      run: echo "result=${{ hashFiles(env.LFS_FILES) }}" | tee -a "$GITHUB_OUTPUT"
+      # GitHub's expression context doesn't support either a literal newline or an escaped newline. We have to use the JSON parser to get a newline character.
+      run: echo "result=${{ hashFiles(join(fromJson(env.LFS_FILES), fromJson('"\n"'))) }}" | tee -a "$GITHUB_OUTPUT"
       
     - name: Cache git lfs
       id: lfs-cache
@@ -182,7 +183,7 @@
 
     - name: Fetch lfs data
       if: ${{ steps.lfs-cache.outputs.cache-hit != 'true' }}
-      run: git lfs fetch --include '${{ env.LFS_FILES }}'
+      run: git lfs fetch --include '${{ join(fromJson(env.LFS_FILES), ',') }}'
   
   test-stable:
     name: cargo test
@@ -215,7 +216,10 @@
           enableCrossOsArchive: true
   
       - name: Checkout LFS files
-        run: git lfs checkout '${{ env.LFS_FILES }}'
+        # `git lfs checkout` requires that each individual glob is a separate command line argument.
+        # The string `''' '''` is how you write `' '` in GitHub's expression context (i.e. two quotes separated by a space)
+        # The quotes are to avoid the shell from evaluating the globs itself.
+        run: git lfs checkout '${{ join(fromJson(env.LFS_FILES), ''' ''') }}'
         continue-on-error: true
 
       - name: install stable toolchain