perf-tool: Add --wrap to wrap the gnome-shell call

perf-tool: Add --wrap to wrap the gnome-shell call

This allows neat tricks like first arranging the script `fakegdb`:

```sh

function ignore_gdb_arg() {
    if [[ "$1" == "--quiet" ]] || [[ "$1" == "--args" ]]; then
	    return 1
    else
	    return 0
    fi
}

ignore_gdb_arg "$1" || shift
ignore_gdb_arg "$1" || shift

echo exec "$@"
```

then running

```sh
meson test -C build -v perf-basic --test-args '--wrap "gdb --args"' --gdb --gdb-path `which fakegdb`
```

To make it possible to run the perf test case with gdb running the
actual gnome-shell.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1349>