feat: user event paste

[mdjastrzebski]

Summary

User Event paste() function with following signature:

function paste(element: ReactTestInstance, text: string);

This function simulates user interaction when user focuses a text input, (select all text if present), pastes given text, and finally leaves the text input.

In the basic for no options are accepted but if needed, they might be added in a future PRs.

Experimental event sequence.

Details

The signature of the function is based on User Event v13 variant: paste(element, dataOrText) and not User Event v14 variant: paste(dataOrText).

Although we generally subscribe to v14 API convention, however there were two issues with it:

1. More difficult API:

const element = screen.getByRole('textbox', {name: /paste your greeting/i})
await userEvent.click(element) // This focuses the element 
await userEvent.paste(text) // This pastes to the current element

Many users complained about the modified API or found it confusing: orig UE issue (4 negative votes), UE PR (11 negative votes), SO issue, UE issue.

2. RNTL currently does not maintain any runtime state of elements, like currently focused element, which would be required to implement v14 approach. Implementing such "runtime state" API, while possible would require breaking changes to do properly.

Test plan

Confirm experimental behavior using automated tests.