Fix clipboard display bug in browse mode if clipboard is empty

[ibrahim-s]

Link to issue number:

Fixes #95

Summary of the issue:

Current NVDA versions no longer expose windll through the winUser module.
Calling:

winUser.windll.user32.EnumClipboardFormats(0)
raises:
AttributeError: module 'winUser' has no attribute 'windll'
when executing the command to show clipboard raw text.

### Description of how this pull request fixes the issue:

The change replaces the call with:
from ctypes import windll
windll.user32.EnumClipboardFormats(0)
which restores compatibility with current NVDA versions.

### Testing performed:
 - tested with empty clipboard,and the appropriate message was heard, denoting that clipboard is empty.
 - Copy a file, and test the gesture to display text in browse mode, the appropriate message heard, denoting that clipboard has content, but couldn't be displayed in browse mode.
 
### Known issues with pull request:
None
### Change log entry:
I noticed that the issue was in NVDA 2026.1 and not reported, and since it is only ppresent if clipboard empty, may be it is very specific and aside issue, and no need for changelog.

[ibrahim-s]

Hi @nvdaes
Really, I am not sure if recent NVDA releases would handle or deal with the issue in a different way, so feel free to change anything, since you know recent api changes more than me, and thank you for giving me this opportunity .
kind regards