tasklist_in_table: parse a tasklist item if it's the only content of a table cell.

[kivikakk]

Musing over this idea (idea originated here).

For when lists just won't do.

e.g.

|     | Task description | URL |
| --- | ---------------- | --- |
| [x] | Do thing.        | ... |
| [ ] | Do other thing.  | ... |

[github-actions]

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
./bench.sh ./comrak-357ced2	315.6 ± 2.6	311.1	322.5	2.96 ± 0.03
./bench.sh ./comrak-main	316.1 ± 2.9	311.6	322.6	2.97 ± 0.03
./bench.sh ./pulldown-cmark	106.5 ± 0.8	105.0	108.5	1.00
./bench.sh ./cmark-gfm	115.9 ± 1.4	113.8	119.3	1.09 ± 0.02
./bench.sh ./markdown-it	497.9 ± 8.2	483.5	517.5	4.67 ± 0.08

Run on Wed Oct 15 06:41:11 UTC 2025