fix(IText): regain focus on mouse move

[ShaMan123]

fixes #8177 caused by #3759 (that was hacky) and fixes #3661 that was the motivation for #3759

This issue was caused because the hiddenTextarea looses focus after mousedown.
So I have added a focus call in mousemove that fixes both issues.

[github-actions]

Code Coverage Summary

> [email protected] coverage:report
> nyc report --reporter=lcov --reporter=text

-----------|---------|----------|---------|---------|-----------------------------------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                             
-----------|---------|----------|---------|---------|-----------------------------------------------
All files  |    82.1 |    74.56 |   84.46 |    80.7 |                                               
 fabric.js |    82.1 |    74.56 |   84.46 |    80.7 | ...,27453,27511,27521-27565,27673,27760,27964 
-----------|---------|----------|---------|---------|-----------------------------------------------

[asturur]

We need to backport this to 5.x too

[asturur]

To be clear #3759 was as hacky as this newer fix.
It restored focus on mouseout. this restore focus on mousemove.
I fail to understand how this is more solid that the other.
The old code was losing focus on textinput because hovering on textinput equal to a mouseout from canvas and so it was triggering.
With this new fix hovering over the itext will loose focus anyway from the newly selected text input. or am i wrong?

[ShaMan123]

this is why it is more solid
focusing will trigger only if in editing mode and after mousedown

[ShaMan123]

We need to backport this to 5.x too

why are we putting effort into v5?
Done e8704f4