Time Travel - support custom ranges

[fbarl]

As @LiliC suggested recently, it would be nice if users could choose the time range they are looking at manually (instead of having to stick to the default values, which are currently 15min, 30min, 1h, 3h, 6h and 24h).

The way we could implement that in the UI is by making the dropdown editable - so it would really be an input box which could show the current defaults in a dropdown if the input is an empty string, or something similar.

cc @bia

[rade]

I am not convinced of the need for this. Our range selection is pretty dense, and there is no point going much below 15min (metrics resolution isn't that fine-grained) or above it (query performance will deteriorate rapidly), though I'd be happy to stretch the range a bit.

OTOH, no objection if this is just a few minutes work.

[fbarl]

Will de-assign myself for now and try to address it later as a part of the new Time Travel UI - https://github.com/weaveworks/ui-components/issues/226.

[ngehani]

If there are no objections, we can just close this issue since it is linked to #226 and if needed can be re-visited. I don't see a need. Even in convo with AWS, the minimum of an hour was enough and we already go down the 15 minutes. Allowing for editing finer controls than that, I don't see a strong enough use case that solves a particular customer problem.