refactor: split CSS class tasks-modal-section

[ilandikov]

Description

• Split tasks-modal-section class into classes depending on their content (date, recurrence, description, etc)
• Remove some unused properties
• Use <section> elements to make the HTML code more explicit semantically
• Remove a nesting level (<div> at the top level of the modal)
• Remove redundant comments
• Slight change in the look of the modal

Motivation and Context

Make possible extraction of components from EditTask.scss and EditTask.svelte. Now CSS class tasks-modal-section contains properties related to all the sections (dependencies, dates, description, etc) that makes that impossible.

How has this been tested?

Some changes were covered by unit tests, but most of them verified by manual test in demo vault.

Screenshots

Before	After

Types of changes

Internal changes:

• Refactor (prefix: refactor - non-breaking change which only improves the design or structure of existing code, and making no changes to its external behaviour)

Checklist

• My code follows the code style of this project and passes yarn run lint.
• My change has adequate Unit Test coverage.
  • No test coverage on the CSS code

Terms

• My contribution follows this project's contributing guide
• I agree to follow this project's Code of Conduct

[ilandikov]

@claremacrae the diff of the .svelte file is not rendered well on GitHub due to one nesting level on very top being gone now (a <div> removed), I suggest taking a look at it in WebStorm the changes are seen in a clearer way.

[claremacrae]

I viewed the final diffs and they made sense. I did a very very quick test that of the dialog and it behaved fine.

Just a minor comment for my own education...