Problem: novice users relying on vimtutor won't know what to do when they follow the instructions and delete a couple lines and that breaks the line checker

Solution: tell the user to fix the line numbers after they're done

Problem: In line 308 the poem appears as

✅1)  Roses are red,
✅2)  Mud is fun,
✅3)  Violets are blue,
✅4)  I have a car,
✅5)  Clocks tell time,
✅6)  Sugar is sweet
✅7)  And so are you.

where the wrong lines (2, 4, 5) are all marked as correct.

Solution: Change the tutor.json file so that initially the poem appears
as

✅1)  Roses are red,
❌2)  Mud is fun,
✅3)  Violets are blue,
❌4)  I have a car,
❌5)  Clocks tell time,
❌6)  Sugar is sweet
✅7)  And so are you.

The method for checking whether a line is correct or not is really
simple, so I couldn't find a way to display the 6th line as initially
correct, however upon deleting lines 2, 4 and 5 the final result shows
line 6 as correct.

Co-authored-by: Danymat <d.danymat@gmail.com>
Co-authored-by: Gregory Anders <greg@gpanders.com>
Co-authored-by: Jakub Okoński <jakub@okonski.org>
Co-authored-by: John L. Villalovos <john@sodarock.com>
Co-authored-by: Maria José Solano <majosolano99@gmail.com>
Co-authored-by: Michaili K <git@michaili.dev>
Co-authored-by: TheLeoP <eugenio2305@hotmail.com>
Co-authored-by: Tobias Schmitz <tobiasschmitz2001@gmail.com>
Co-authored-by: W20MC <157727813+W20MC@users.noreply.github.com>
Co-authored-by: Will Hopkins <willothyh@gmail.com>
Co-authored-by: Yifan Hu <141280278+b0ae989c@users.noreply.github.com>
Co-authored-by: glepnir <glephunter@gmail.com>
Co-authored-by: prljav <74116121+prljav@users.noreply.github.com>

Co-authored-by: ite-usagi <77563904+ite-usagi@users.noreply.github.com>
Co-authored-by: v-sim <56476039+v-sim@users.noreply.github.com>
Co-authored-by: Evgeni Chasnovski <evgeni.chasnovski@gmail.com>
Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Co-authored-by: Quico Augustijn <quico.public@gmail.com>
Co-authored-by: nhld <nahnera@gmail.com>
Co-authored-by: francisco souza <108725+fsouza@users.noreply.github.com>

Co-authored-by: C.D. MacEachern <craig.daniel.maceachern@gmail.com>
Co-authored-by: Ynda Jas <yndajas@gmail.com>
Co-authored-by: Owen Hines <TheOdd@users.noreply.github.com>
Co-authored-by: Wanten <41904684+WantenMN@users.noreply.github.com>
Co-authored-by: lukasvrenner <118417051+lukasvrenner@users.noreply.github.com>
Co-authored-by: cuinix <915115094@qq.com>

Problem:  URLs in :Tutor use "http" instead of "https".
Solution: Update URLs with a valid "https" equivalent.

Add Japanese Tutor

Co-authored-by: Patrick Bollinger <owner@pjbollinger.com>
Co-authored-by: vilo1839 <139687192+vilo1839@users.noreply.github.com>

Problem:
Some steps in :Tutor don't work on Windows.

Solution:
Add support for `{unix:...,win:...}` format and transform the Tutor contents
depending on the platform.
Fix https://github.com/neovim/neovim/issues/24166