warning WebUI is installed under a dot directory

[w-e-w]

Description

detects and show a warning if WebUI is installed under a dot directory whitch will break the webpage as lots of files are blocked

this is a long-standing issue see

• Do not installed Webui under a directory with leading dot (.) #13292

even though I have pind the issue on top of the issue page
I still see people faceing this issue from time to time

so better to add big a warning

• this issue should get resolve when Gradio 4 #14184 is merged
• • no idea when that will happen
• this warning should be removed in the future when it's no longer necessary

Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests