[Enhancement] V2: Allow ⪆ `31.0.10` to render non-block CommonMark (including HTML5) in task titles.

[RokeJulianLockhart]

What Problems This Relates To

tasks/tasks supports it, so when my tasks synchronize, they are significantly less legible from the Nextcloud Tasks interface.

Desired Solution

Render non-block CommonMark (including HTML5) in task titles.

Considered Alternatives

I've yet to think of any.

Additional Context

1. gitlab.com/gitlab-org/gitlab/-/issues/577274 cites examples of where else this has been implemented. GitHub and GitLab are examples, as should be Forgejo.

2. Replaces issues/2191#issuecomment-2526189903. Previously, I forgot to state that I wanted this to render in titles. To ensure that issues/2191#issuecomment-1416677558 doesn't repeat, I disclaim that issues/1486 solely refers to CommonMark within the note field, whereas issues/2274 refers to HTML5 within the note field.