Allow to override the shell for contributed tasks

[dbaeumer]

See #36216 why that would be useful.

[ramya-rao-a]

@dbaeumer Is this still meant for the January milestone? If not, can you move it to February milestone?

[dbaeumer]

To verify specify a different shell for a type script build task. For example for Windows configure cmd.exe.

        {
            "type": "typescript",
            "tsconfig": "tsconfig.json",
            "option": "watch",
            "options": {
                "shell": {
                    "executable": "C:\\Windows\\System32\\cmd.exe",
                    "args": [
                        "/d", "/c"
                    ]                    
                }
            },
            "problemMatcher": [
                "$tsc-watch"
            ]
        }