ui: Added support for now keyword in time range selector

[manojVivek]

Resolves #4212

[alwaysmeticulous]

✅ Meticulous spotted zero visual differences across 396 screens tested: view results.

_{Last updated for commit fd28518. This comment will update as new commits are pushed.}

[yomete]

lgtm!

[brancz]

I don't think the behavior requested in #4212 is quite what was implemented here.

Personally I'd be perfectly happy with just now as an "alias" for the current time.

I don't think the expected behavior is to literally replace the "now" with the timestamp, but rather keep "now" and transparently use the current timestamp when running the query. We would have to keep both the "meta value" like "now" in the URL as well as the "real" timestamp used to run the last query so we have all the state persisted in the URL.

I do think this also requires us to replace the built-in datetime picker with a custom one where one would be able to pick "now" (and potentially other meta values like "15min ago" in the future but I would skip other things for now).

[manojVivek]

I don't think the expected behavior is to literally replace the "now" with the timestamp, but rather keep "now" and transparently use the current timestamp when running the query. We would have to keep both the "meta value" like "now" in the URL as well as the "real" timestamp used to run the last query so we have all the state persisted in the URL.

Yes, this what Yomi and I finalised on Discord as well, will change the implementation.

[manojVivek]

Superseded by #4248