feat: Canvas snapshots for `freya-testing`

[marc2332]

Closes https://github.com/marc2332/freya/issues/702

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 4.65116% with 41 lines in your changes missing coverage. Please review.

Project coverage is 73.87%. Comparing base (5d99dbe) to head (32675a4). Report is 2 commits behind head on main.

:exclamation: Current head 32675a4 differs from pull request most recent head 47e4cb7

Please upload reports for the commit 47e4cb7 to get more accurate results.

Files	Patch %	Lines
crates/testing/src/test_handler.rs	0.00%	41 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #720 +/- ## ========================================== - Coverage 73.91% 73.87% -0.04% ========================================== Files 198 197 -1 Lines 20321 20447 +126 ========================================== + Hits 15020 15106 +86 - Misses 5301 5341 +40 ```

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[github-actions[bot]]

Benchmark for fc0601a

Click to view benchmark

| Test | Base | PR | % | |------|--------------|------------------|---| | benchmarks/alignments=true size=21845 depth=8 wide=4 mode=not cached | 111.5±0.70ms | **110.0±0.56ms** | **-1.35%** | | benchmarks/size=100001 depth=2 wide=100000 mode=not cached | 26.6±0.62ms | 26.2±0.78ms | -1.50% | | benchmarks/size=10001 depth=2 wide=10000 mode=not cached | 1448.2±19.99µs | 1454.6±13.44µs | +0.44% | | benchmarks/size=1001 depth=2 wide=1000 mode=not cached | 141.3±1.30µs | 141.8±1.55µs | +0.35% | | benchmarks/size=131071 depth=17 wide=2 mode=not cached | 25.4±0.53ms | 25.5±0.55ms | +0.39% | | benchmarks/size=16383 depth=14 wide=2 mode=not cached | 1724.9±11.64µs | 1715.5±13.90µs | -0.54% | | benchmarks/size=19531 depth=7 wide=5 mode=cached | 340.1±13.43µs | 338.5±11.90µs | -0.47% | | benchmarks/size=19531 depth=7 wide=5 mode=not cached | 2.7±0.14ms | 2.7±0.06ms | 0.00% | | benchmarks/size=4095 depth=12 wide=2 mode=not cached | 416.9±37.27µs | 417.3±58.39µs | +0.10% | | benchmarks/size=54241 depth=5 wide=15 mode=cached | 283.9±26.51µs | 293.1±24.40µs | +3.24% | | benchmarks/size=54241 depth=5 wide=15 mode=not cached | 6.6±0.12ms | 6.5±0.14ms | -1.52% |