vscode: Missing partial icon and color API support for ExtensionTerminalOptions and TerminalOptions

[rschnekenbu]

With #11504, the added API was partially stub. Currently, only a ThemeIcon is supported, while the vscode API provides also support for URI and {dark: URI, liught: URI}. Also the color icon support has been stubbed, as the current implementation of the title widget as terminal title does not let an easy customization of the icon color.

[kittaakos]

From #12645 (comment):

ExtensionTerminalOptions#iconPath is currently unsupported by Theia.

Create a terminal with vscode.window.createTerminal(options: ExtensionTerminalOptions): Terminal, set the iconPath to heart.

VS Code:

Theia:

Feature Description:

ExtensionTerminalOptions#iconPath works as in VS Code.

[dhuebner]

I will take the PR over to apply the review suggestions.