Add TickStats aggregation and rename TimeSeriesStats

[MHHukiewitz]

The class in timeSeries.ts is currently being used to aggregate event-level data in intervals called TimeFrames.

These come close to the concept of "Candlestick" data, and I propose to rename them accordingly due to the misleading naming as "TimeSeries" which simply means:

A time series is a sequence of data points that occur in successive order over some period of time.

In my latest work on integrating SPL Lending program's instructions into the TokenSnapshot indexer, I have the requirement to efficiently aggregate all events such that a linked and aggregated data point will be created for every event to receive tick-level data. A tick describes:

A tick is a measure of the minimum upward or downward movement in the price of a security. A tick can also refer to the change in the price of a security from one trade to the next trade.

Suggested changes

• Following the latter definition, I would suggest implementing a new type of stats aggregator: TickStats for event-level aggregation of statistics.
• The previously called TimeSeriesStats and all related classes/variables could be renamed to CandlestickStats, to appeal to DeFi users, or more generally, IntervalStats.

Note: These two steps should be conducted in two separate PRs.