7703 metricsql support metric names in quotes as alternative to name metric pattern

[possibull]

Enhance MetricsQL to support quoted UTF8 label names

[possibull]

It would seem prettifier.go does not use the same WITH expand (which is where all the code to generate metricName is) as Parse(). It first uses parseInternal() and then does its own parsing via appendPrettifiedExpr(). This would need to be changed to get prettify to work properly. This was not caught originally because the case {"foo"} was not an accepted case before.
The good news is this only affects the construction of metricName and adding it to be parsed by getMetricName()

case *MetricExpr:
		// Split:
		//
		//   metric{filters1 or ... or filtersN}
		//
		// into:
		//
		//   metric{
		//     filters1
		//       or
		//     ...
		//       or
		//     filtersN
		//   }
		lfss := t.labelFilterss
		offset := 0
		metricName := getMetricNameFromLabelFilterss(lfss)
		if metricName != "" {
			offset = 1
		}
		dst = appendIndent(dst, indent)
		dst = appendEscapedIdent(dst, metricName)
		if !isOnlyMetricNameInLabelFilterss(lfss) {
			dst = append(dst, "{\n"...)
			for i, lfs := range lfss {
				lfs = lfs[offset:]
				if len(lfs) == 0 {
					continue
				}
				dst = appendPrettifiedLabelFilters(dst, indent+1, lfs)
				dst = append(dst, '\n')
				if i+1 < len(lfss) && len(lfss[i+1]) > offset {
					dst = appendIndent(dst, indent+2)
					dst = append(dst, "or\n"...)
				}
			}
			dst = appendIndent(dst, indent)
			dst = append(dst, '}')
		}
		```

[hagen1778]

LGTM!
A few minor comments