[Feature] Support gauge_agg accessor function RATE

[yukkit]

Is your feature request related to a problem? Please describe.
Calculate the rate of change of the gauge_agg. This is the simple rate, equal to the last value minus the first value, divided by the time elapsed.

The unit of time_delta is determined by the time unit of the time column:

time_delta	time column
ms	s
	ms
ns	us
	ns

Describe the solution you'd like

• Syntax

RATE(<GaugeAgg>): <rate value>

• arguments

GaugeAgg: The result of aggregate function GaugeAgg, see https://github.com/cnosdb/cnosdb/issues/1365

• returns

rate value: The data type is consistent with the argument 'gauge' in 'GaugeAgg' func.

Describe alternatives you've considered

Add to https://github.com/cnosdb/cnosdb/tree/main/query_server/query/src/extension/expr/scalar_function

Additional context

The mainstream database supports RATE show below:

timescaledb
https://docs.timescale.com/api/latest/hyperfunctions/counters-and-gauges/gauge_agg/#rate