Improve custom time range UI in dashboard

[KaiOelfke]

Say I want to compare a funnel insight for this month vs last month I may open two tabs and pick a different time range.

The UX for updating the time range is currently not good:

• the page will eventually reload potentially losing some pending edits in the time range UI
• I can't type in a number like 45 days and I often have to click 30 times to go from 30 days to one month
• It's not intuitive which arrow increases / decreases the number
• I can't do multiple edits as the page will reload according to bullet point one

[winsmith]

Other customer:

I would like to simply specify a custom weekly date range like “Sep 4-10, 2023”. And then navigate the weeks back and forth. The custom range picker has some weird date controls that don’t let me do this.

[winsmith]

Thanks! Closing this as a duplicate of https://github.com/TelemetryDeck/web/issues/1475