xtask with Kompari (#1019)

This PR adds xtask similar to
linebender/parley#272 for Parley.
Because Vello has two types of tests: snapshots and comparisons (cpu vs.
gpu),
xtask is divided to two subcommands:

```
cargo xtask snapshots ...
cargo xtask comparisons ...
```

The first one offers all Kompari's functionality (report, review,
size-check, dead-snapshots detection).
The second one offers only report as others do not make sense.

Btw1: Current size check output:


![image](https://github.com/user-attachments/assets/3d51a8d1-9b7c-4a99-a0b0-c291a8f7588d)

Btw2: Current dead snapshots report (This may be broken as some tests
are skipped on my machine)

```
/home/ada/projects/vello/vello_tests/current/big_bitmap.png
/home/ada/projects/vello/vello_tests/current/big_bitmap_apple.png
/home/ada/projects/vello/vello_tests/current/big_colr.png
/home/ada/projects/vello/vello_tests/current/bitmap_undef.png
/home/ada/projects/vello/vello_tests/current/blurred_rounded_rect.png
/home/ada/projects/vello/vello_tests/current/colr_undef.png
/home/ada/projects/vello/vello_tests/current/deep_blend.png
/home/ada/projects/vello/vello_tests/current/fill_types.png
/home/ada/projects/vello/vello_tests/current/funky_paths.png
/home/ada/projects/vello/vello_tests/current/gradient_extend.png
/home/ada/projects/vello/vello_tests/current/image_extend_modes_bilinear.png
/home/ada/projects/vello/vello_tests/current/image_extend_modes_nearest_neighbor.png
/home/ada/projects/vello/vello_tests/current/image_sampling.png
/home/ada/projects/vello/vello_tests/current/integer_translation.png
/home/ada/projects/vello/vello_tests/current/little_bitmap.png
/home/ada/projects/vello/vello_tests/current/little_colr.png
/home/ada/projects/vello/vello_tests/current/longpathdash_butt.png
/home/ada/projects/vello/vello_tests/current/many_clips.png
/home/ada/projects/vello/vello_tests/current/non_integer_translation.png
/home/ada/projects/vello/vello_tests/current/rounded_rectangle_watertight.png
/home/ada/projects/vello/vello_tests/current/scaled_hinted.png
/home/ada/projects/vello/vello_tests/current/simple_hinted.png
/home/ada/projects/vello/vello_tests/current/smoke/data_image_roundtrip.png
/home/ada/projects/vello/vello_tests/current/smoke/filled_circle.png
/home/ada/projects/vello/vello_tests/current/smoke/filled_square.png
/home/ada/projects/vello/vello_tests/current/smoke/two_emoji.png
/home/ada/projects/vello/vello_tests/current/splash.png
/home/ada/projects/vello/vello_tests/current/stroke_styles.png
/home/ada/projects/vello/vello_tests/current/stroke_styles_non_uniform.png
/home/ada/projects/vello/vello_tests/current/stroke_styles_skew.png
/home/ada/projects/vello/vello_tests/current/tricky_strokes.png
```

Author: spirali

.cargo/config.toml

@@ -6,3 +6,4 @@ run_wasm = "run --release --package run_wasm --"
 # Other crates use the alias run-wasm, even though crate names should use `_`s not `-`s
 # Allow this to be used
 run-wasm = "run_wasm"
+xtask = "run --release --package xtask --"

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ env:
   FEATURES_DEPENDING_ON_STD: "std,default,png,pico_svg,multithreading"
   # List of packages that can not target Wasm.
   # `vello_tests` uses `nv-flip`, which doesn't support Wasm.
-  NO_WASM_PKGS: "--exclude vello_tests"
+  NO_WASM_PKGS: "--exclude vello_tests --exclude xtask"
   # The files stored in LFS the tests need to access, in JSON format
   LFS_FILES: '["vello_tests/snapshots/*.png", "sparse_strips/vello_sparse_tests/snapshots/*.png"]'