feat: removed non-official themes from the settings dialog

[kittaakos]

## Depends on #1988 ✅

Motivation

This PR updates the behavior or the theme <select> in the Settings dialog and makes it overall easier to "install" and use custom (VS Code extension-based) themes in IDE2.

Change description

1. IDE2 shows only Light, Dark, and High Contrast themes in the Settings dialog.

1283_01.mp4

2. This PR does not change the fully qualified name of the Arduino themes or the behavior of the Preferences: Color Theme command contributed by Theia. (Or with the Ctrl/⌘+K Ctrl/⌘+T key-chord.) Experienced users should use this command to list and select unofficial themes. The quick-pick theme items show the fully qualified names of the Arduino themes to follow the naming convention among the VS Code extension-based themes. This PR does not change the behavior of the workbench.colorTheme preference.

1283_02.mp4

3. This PR fixes the location of the default plugin (VS Code extension) drop-in folder. With this, there is no need to copy the custom themes inside the application (Remove deprecated Theia themes #1283 (comment)). It is sufficient to copy the theme VSIX to the shared drop-in folder. If you have unofficial themes in the plugins folder, you can list them and select one with the Preferences: Color Theme command:

• If you are using Windows:

  C:\Users\<username>\.arduinoIDE\plugins\
  

  (where <username> is your Windows username)
• If you are using Linux:

  ~/.arduinoIDE/plugins/
  

  (XDG_CONFIG_HOME is not supported Theia apps: option to respect each operating system standards when chosing their user-level config folder path eclipse-theia/theia#1518)
• If you are using macOS:

  ~/.arduinoIDE/plugins/
  

1283_03.mp4

5. The Settings dialog is backward compatible. If you select a non-official theme, it will work after this update. IDE2 will show Unofficial - ${THEME_NAME} as the <select> label.

1283_04.mp4

6. When an unofficial theme is selected, the Settings dialog shows Unofficial - ${THEME_NAME}. When you unselect the unofficial <select> label, it won't be possible to select it again. Users must cancel the Settings dialog or use a command or the advanced settings to select custom, unofficial themes.

1283_05.mp4

7. This PR handles obsolete themes. If a VSIX theme is deleted from the drop-in plugins folder, IDE2 detects it on startup and selects a compatible theme from the built-in ones.

1283_06.mp4

Other information

Closes #1283
Closes #1851

Reviewer checklist

• PR addresses a single concern.
• The PR has no duplicates (please search among the Pull Requests before creating one)
• PR title and description are properly filled.
• Docs have been added / updated (for bug fixes / features)

[per1234]

Users must cancel the Settings dialog or use a command or the advanced settings to select custom, unofficial themes.

Although this is an excellent approach to migrating people away from the deprecated built-in Theia themes (#1283), it harms the user experience when using manually installed themes. It was decided that manual installation of theme extensions will be officially supported (though of course Arduino does not maintain or provide support for the individual 3rd party themes themselves). So we do need to give consideration to that use case.

Would it be possible to apply this behavior (only showing the theme in the "Theme" menu of the "Preferences" dialog if already selected) exclusively to the deprecated built-in Theia themes rather than applying it to the manually installed theme extensions in ~/.arduinoIDE/plugins as well (as is currently done by the PR)? Since it is an officially supported use case, I think the user should be able to select a manually installed 3rd party or custom theme from the "Preferences" dialog (as is the behavior in Arduino IDE 1.x).

[kittaakos]

Thank you for the review. I made the requested changes, and the build is running.

Instead of updating the original description of this PR and replacing the screencasts, this section shows the differences between the latest review.

• User-installed (VSIX) themes are always visible in the Settings dialog theme dropdown.
• User-installed theme labels have the (user) suffix.
• If the currentTheme is either Light (Theia) or Dark (Theia), it will be visible from the dropdown with the (deprecated) suffix.
• The themes in the <select> dictates the following ordering:
  • Light,
  • Dark,
  • Hight Contrast,
  • User-installed themes grouped by light, dark, and hc type. If the type equals, sorting is done by the theme label,
  • Deprecated theme comes last:

1283.mp4

[per1234]

Thanks Akos!

[kittaakos]

With the most recent changes, the themes are grouped by built-in, user, and deprecated groups. All the sorting and the behavior must be the same.

1283_separator.mp4

[per1234]

Looks great. Thanks!