Add extra_selectors and sum_by for latency recording rule panel

[jiachengxu]

Signed-off-by: Jiacheng Xu [email protected]

What this PR does: This PR adds two options to pass the extra_selectors and sum_by to the latencyRecordingRulePanel function. This is really useful when Prometheus adds external labels (cluster labels) before sending the recording metrics to Cortex

Which issue(s) this PR fixes: Fixes #

Checklist

• [x] CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

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