[vscode] support git blame information with status bar and editor decoration features via git built-in extension

[ndoschek]

Feature Description:

Add support for advanced git blame features in the updated built-in Git extension.
The git blame features are available via the toggleable statusbar item and/or editor decorations (see also https://code.visualstudio.com/docs/sourcecontrol/overview#_git-blame-information for more info).

Features to implement:

• Introduce MultiDiffEditor (see also https://code.visualstudio.com/updates/v1_86#_review-multiple-files-in-diff-editor)
• Handle _workbench.openMultiDiffEditor command triggered by git blame (via status bar or editor decorations)
• Support theia.proposed.statusBarItemTooltip, introducing tooltip factories
• Implement getTextEditorDiffInformation in TextEditorsMainImpl to provide detailed diff context, e.g., for git blame features among others

Prerequisites:

• [vscode] API evolution (public and proposed) and menu extension points between 1.102 and 1.104 #16134 (API evolution to 1.104.0)
• [vscode] update VS Code built-in extensions #16279 (update of built-ins)