Add timestamp handling to logs

What does this MR do and why?

This MR includes a set of changes required for Log entry details should be shareable (gitlab-org/opstrace/opstrace#2676 - closed)

More specifically it adds timestamp params handling to logs related logic.

• Add support for timestamp params to fetchLogs API: when a timestamp is provided, we need to set start_time and end_time to the given timestmap
• Add timestamp handling to dateRange query utils: Adds timestamp logic to query params handling utils

I've also include a fix for a tiny bug where the filtered-search-term was not reset correctly.

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