Allow events to be replaced

[gonzofish]

Addresses #150

• Moved code for adding an event to addEventHandler
• Moved code for removing an event to removeEventHandler
• Created utility function for formatting plotly event names
• Added 3rd condition to syncEventHandlers that will replace a handler if it is not the already-stored handler

[FloChehab]

Hi, I was having a similar issue as described in #150 yesterday. I just wanted to say that I have tested the code from this PR and it indeed solves the issue in my case.

Thanks ! 😄

[gonzofish]

Glad I could help @FloChehab...my issue became with using hooks, where the callback function that got called was a number of renders ago. My solution ended up using useCallback to keep a memoized reference

[korommatyi]

Can some of the maintainers please take a look? We are facing the same issue, would be nice to be able to update event handlers.

[nicolaskruchten]

@VeraZab @dmt0 can you guys please merge this and release it and then incorporate it into the next build of RCE, which should also include plotly.js 1.50.1?

[nicolaskruchten]

@gonzofish thanks for this PR, and my apologies it took so long to get it looked at :)