feat(notes): sort notes by name, date modified or date created

[dionmunk]

Notes and folders were always sorted by name (#22, #63).

Changes

• Sort By button after Search in the title bar of Notes and Workspace Notes. It opens a short list: Name A to Z (the default), Name Z to A (asked for in Sort Notes by Modified/Creation Date #63), Date Modified newest first, and Date Created newest first. The current order is marked with a check.
• The choice is saved in a new notes.sortOrder setting, so it persists and also shows in Settings, like the Explorer's explorer.sortOrder. It's written to the user settings, or to the workspace settings when they already set it.
• Folders stay first, as in the Explorer. Dates are read only when a date order is chosen. Where a file system doesn't record when a file was created, the date modified is used.
• List Notes (Alt+L) orders the notes after the recently opened ones (feat(notes): show recently opened notes first in List Notes #102) the same way.
• Refresh and Settings move to the ... menu of each section, next to Reveal in File Explorer and the location commands, so the title bar shows New Note, New Folder, Search and Sort By.

Extensions can't show a check mark on a menu item: the schema for contributes.commands in VS Code 1.140 has category, command, icon, enablement, shortTitle and title, and menu items have command, alt, group, submenu and when, but no toggled. That's why the button opens a list (like the Extensions view's filter) rather than a menu of checked items (like Outline's Sort By, which is built into VS Code).

Testing

• npm test: 41 passing, 6 new tests for the order (each order, folders first, the same date falling back to the name, an unknown setting).

• End to end in VS Code 1.140 on macOS. Notes and folders were created a second apart (archive, work, alpha, beta, gamma), then alpha was rewritten and a note was added to archive, so the two date orders differ:

  Sort by	Tree
  Name, A to Z	archive, work, alpha, beta, gamma
  Name, Z to A	work, archive, gamma, beta, alpha
  Date Modified	archive, work, alpha, gamma, beta
  Date Created	work, archive, gamma, beta, alpha

  Each choice was saved as notes.sortOrder in the user settings, the list marked the current order with a check, and List Notes followed Date Modified (old.md, in archive, changed last, came first).

• Title bar and ... menu, with Notes only and with both sections:

  • icons: New Note, New Folder, Search, Sort By
  • Notes ...: Reveal in File Explorer, Set Up Workspace Notes (when the workspace has no notes), Refresh Notes, Settings
  • Workspace Notes ...: Reveal in File Explorer, Select Workspace Notes Location, Refresh Notes
  • Refresh Notes and Settings work from the menu; Settings opens filtered to Notes, with the new Sort Order setting.

• Not tested: Windows and Linux; on Linux, whether a file's creation date is available depends on the file system.

Closes #22, closes #63.