Time-series aggregation functions

[dnhatn]

Here is the list of time-series aggregation functions we aim to support. Feel free to add more and assign your name to a function.

• rate: Add rate aggregation function #106703
• irate
• increase
• delta
• idelta

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• max_over_time: Add max_over_time aggregation for TSDB #126498
• min_over_time: Add min_over_time #127649
• avg_over_time: Add avg_over_time #126572
• count_over_time: Count and Count distinct functions for tsds #128530
• distinct_over_time: Count and Count distinct functions for tsds #128530
• sum_over_time: Add sum_over_time aggregation #128413
• last_over_time: Add last_over_time #126650 (needs to support all types)
• first_over_time: Add first_over_time #127656

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[elasticsearchmachine]

Pinging @elastic/es-storage-engine (Team:StorageEngine)

[dnhatn]

I think we can generate {agg}_over_time aggregation functions instead of writing them by hand.

[jdcryans]

We'll track the remaining functions in #129014 as we're not planning to work on those right away.