Add default fileNesting contributions

[timheuer]

Describe the solution you would like

Per the docs, extensions can contribute default Explorer fileNestingPatterns: https://code.visualstudio.com/updates/v1_67#_explorer-file-nesting

We should provide a set of defaults as follows:

"explorer.fileNesting.patterns": {
        "*.cs": "${capture}.designer.cs,${capture}.g.cs,${capture}.generated.cs",
        "*.csproj": "${capture}.csproj.user",
        "*.json": "${capture}.Development.json",
        "*.cshtml": "${capture}.cshtml.cs,${capture}.cshtml.css",
        "*.razor": "${capture}.razor.cs,${capture}.razor.css",
        "*.css": "${capture}.css.map"
    }

Applicable Scenarios

Default VS Code explorer view

Additional context

Ionide has done this in ionide/ionide-vscode-fsharp#1724

[heartacker]

remember the xaml,please