feat(time-series): add multi-aggregation range APIs

[nkaradzhov]

Description

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Checklist

• Does npm test pass with this change (including linting)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?

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Note

Medium Risk
Adds new RedisTimeSeries range command variants and reply transformers, which could affect client parsing/typing and output shapes for TS.RANGE/MRANGE-style calls. Changes are read-only and well-tested, but touch RESP2/RESP3 transformations and command argument construction.

Overview
Adds new *MultiAggr TimeSeries commands that allow requesting multiple aggregations in a single range query, returning samples as { timestamp, values: [...] } for TS.RANGE/TS.REVRANGE and multi-key TS.MRANGE/TS.MREVRANGE variants (including WITHLABELS and SELECTED_LABELS).

Introduces shared argument parsing (TsRangeMultiAggrOptions / parseRangeMultiArguments) and new RESP2/RESP3 reply transformers for multi-aggregation samples, wires the commands into the public exports, and updates the README to use TIME_SERIES_AGGREGATION_TYPE plus document the new APIs.

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