Rework MinSize implementation for richtext with wrapping

[dweymouth]

Checklist

• I have searched the issue tracker for open issues that relate to the same problem, before opening a new one.
• This issue only relates to a single bug. I will open new issues for any other problems.

Describe the bug

The current 2-pass implementation seems to have race conditions

How to reproduce

See fyne-contributors Slack discussion from 2024-05-28

Screenshots

No response

Example code

complicated

Fyne version

develop

Go compiler version

n/a

Operating system and version

n/a

Additional Information

No response

[andydotxyz]

I think this also covers the GridWrap layout and widget implementations?

[dweymouth]

Not the widget, I don't think - I believe its minsize is just the template element. I use it extensively and haven't run into the race condition with it. Not sure about the GridWrap layout off the top of my head