Address autolink edge cases.

[kivikakk]

Start of a spike to try addressing autolink edge cases by bringing in the pre-postprocessing (ahem) step from cmark-gfm, and then aligning the postprocessing ones.

Fixes #382, fixes #388, fixes #423, fixes #58 (!).

TODO:

• fix we://w all_options case.
• keep fuzzing.

[github-actions]

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
./bench.sh ./comrak-4587e20	322.2 ± 3.0	318.9	328.1	2.93 ± 0.06
./bench.sh ./comrak-main	317.6 ± 1.6	315.5	323.2	2.89 ± 0.06
./bench.sh ./pulldown-cmark	110.0 ± 2.1	107.9	118.9	1.00
./bench.sh ./cmark-gfm	118.0 ± 0.8	116.7	119.6	1.07 ± 0.02
./bench.sh ./markdown-it	478.2 ± 2.2	474.6	482.5	4.35 ± 0.09

Run on Wed Jul 10 09:16:52 UTC 2024

[kivikakk]

Fuzzed gfm for several hours with no finds; all_options found a few quickly as relaxed_autolinks adds some flavour, but having fixed those reasonably robustly there seems to be nothing left there either. Will keep it running for the next while but I'm happy to merge this now and close a 6½ year old issue (!).

[digitalmoksha]

Wow, nice job @kivikakk! 🚀

[kivikakk]

Thanks so much! I was feeling motivated today 😊