Increase default plotly.js double-click delay to 500ms (from current 300)

[emilykl]

Description

Plotly's current default double-click delay (the maximum time between clicks for them to be counted as a double-click) is 300ms.

This is significantly shorter than the default double-click delay on Windows and Mac, which is 500ms^{1, 2}.

This causes confusion and difficulty when trying to double-click in plotly. I've run into it myself and sometimes needed to try double-clicking several times before I get one that's fast enough. It's a usability and accessibility issue.

It would be even better if we could respect the user's system double-click delay setting, but from what I've learned so far there's no way to gain access to that value in JavaScript. But increasing to match the Mac and Windows system default is at least an improvement over the current behavior.

See previous discussion in #6538, with thanks to @oscarrutt for raising the issue.

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1. Windows: https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-setdoubleclicktime.

2. Mac: My own machine, which I haven't changed from the default:

   % defaults read -g com.apple.mouse.doubleClickThreshold
   0.5