Improve error message when comment too long

[tordans]

Right now, the UI error message for comments that are too long is just

It was not possible to post your comment.

The console is also not helpful.
Only the API response helps with {"comment":["Ensure this field has no more than 1000 characters."]}

The UI should show that the comment cannot be above 1000 chars or at least the error message should.
Remember to include the text that OSMCha adds automatically as well, because that is what pushed my comment (https://www.openstreetmap.org/changeset/139346836#map=17/52.35860/13.61964&layers=N) over the limit…

[martien-176]

https://hotosm.slack.com/archives/CPZV2GQP8/p1692644803509139

I reported this same issue more than 2 weeks ago on the #osmcha Slack channel.

@willemarcel said there that he would increase that 1000 characters limit, obviously this did not happen yet.