Papercut fix: null bytes starting whitespace in sudoers files

[squell]

This is perhaps best reviewed commit by commit.

• First commit unignores the compliance tests
• Second commit fixes the spot where the "illegal escape" error was hidden (which made it harder to find the bug)
• Third commit changes the error into the correct one (escape character is now hardcoded \, no need for a sentinel)
• Fourth commit seems a bit unrelated, but changes the contract of accept_if, which was the only function for which you could rely on an Err result to not have consumed input (which accept_escaped then followed incorrectly) to prevent similar mistakes in the future.

[github-actions[bot]]

Number of dependencies and binary size impact report

Metric	main	PR #751	Delta
Direct dependencies	3	3	-
Total dependencies	4	4	-
Binary size	1 MiB	1023.9 KiB	-0.5%
Text size	597.6 KiB	593.6 KiB	-0.7%

Dependencies diff

```diff └─ sudo-rs [v0.2.0] ├─ glob [v0.3.1] ├─ libc [v0.2.147] └─ log [v0.4.20] ```

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.02% :tada:

Comparison is base (0ac6fa8) 54.86% compared to head (aaf4b7d) 54.88%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #751 +/- ## ========================================== + Coverage 54.86% 54.88% +0.02% ========================================== Files 71 71 Lines 9731 9736 +5 ========================================== + Hits 5339 5344 +5 Misses 4392 4392 ``` | [Files Changed](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/751?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety) | Coverage Δ | | |---|---|---| | [src/sudoers/tokens.rs](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/751?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety#diff-c3JjL3N1ZG9lcnMvdG9rZW5zLnJz) | `96.42% <ø> (ø)` | | | [src/sudoers/ast.rs](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/751?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety#diff-c3JjL3N1ZG9lcnMvYXN0LnJz) | `82.76% <100.00%> (ø)` | | | [src/sudoers/basic\_parser.rs](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/751?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety#diff-c3JjL3N1ZG9lcnMvYmFzaWNfcGFyc2VyLnJz) | `94.73% <100.00%> (+0.02%)` | :arrow_up: | | [src/sudoers/test/mod.rs](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/751?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety#diff-c3JjL3N1ZG9lcnMvdGVzdC9tb2QucnM=) | `92.82% <100.00%> (+0.07%)` | :arrow_up: |

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