Add CLI flags to specify timeframe of analysis

[julia-yin]

What would you like to be added?

Add the ability to specify a timeframe for analyzing an issue - only data from that timeframe will be pulled and analyzed. E.g. last 24 hours, last 2 hours, etc.. There should be a default timeframe (6 hours?) which is used if no custom timeframe is specified. We should also clearly indicate to the user what timeframe is being used for the analysis, if it's the default one or a user-specified time range.

Why is this needed?

For certain issues that require Holmes to look at high volumes of logs/traces, users may run into token limit issues or high latency. Adding this capability to filter based on time range will help reduce the amount of data being analyzed.

[aantn]

#798