linesweeper: keep a copy of the crates.io 0.5.0 package in vendor/

Add the linesweeper 0.5.0 package to vendor/ with no file changed, so
that a fix to it can reach the Craft apps through this repository
without waiting for a linesweeper release. The GitHub repository its
manifest names is archived, and its README says development moved off
GitHub.

Leave out the test font (fonts live in craft-fonts), the logo artwork,
the snapshot images and the package's repository tooling. SOURCE.json
lists each with its hash.

Add a workspace exclude, a [patch.crates-io] entry, SOURCE.json with
the archive hash and per-file hashes, NOTICE and ATTRIBUTION.md rows,
and the package's tests in the backend test script. craft-prepress's
flatten feature now builds against the copy, so Cargo.lock drops the
package's registry source and checksum.

scripts/test-pdf-backends.sh

@@ -16,3 +16,6 @@ for backend in hayro-syntax hayro-interpret hayro hayro-jbig2 hayro-cmap hayro-p
 done
 cargo test --manifest-path "$test_root/hayro-syntax/Cargo.toml" --doc "${patches[@]}"
 cargo test --manifest-path "$test_root/hayro-syntax/Cargo.toml" --lib --no-default-features --features std "${patches[@]}"
+cp -R "$root/vendor/linesweeper" "$test_root/linesweeper"
+cargo test --manifest-path "$test_root/linesweeper/Cargo.toml" --locked --lib --test regression
+cargo test --manifest-path "$test_root/linesweeper/Cargo.toml" --locked --doc