logic and styling to expand and open checklist sections

[ashimupd]

Open all:

All checklist items convert to open state if pressed, regardless of their category or prior state.
If pressed again, checklist items revert to a closed state.

Open section:

If pressed, all checklist items in the relevant section convert to open state, regardless of their category or prior state.
If pressed again, checklist items update to a closed state.

Closes #940

[SaptakS]

@ashimupd thanks for opening a PR. Did you check #1280 ? I think that PR already has a lot of the ideas and discussions, and I would preferably see work done on getting that PR completed, if that makes sense to you. Please check the PR once, and let me know what you think.

[ashimupd]

@SaptakS

Hey, I went through all the discussions in that PR and incorporated that to this one. It made more sense for me to create a new PR considering that PR was pretty old! Let me know what you think!