[win32] Fix scaling inside Region::intersect

[akoch-yatta]

This commit adresses possibly invalid result when using Region::intersects on a zoom not dividable by 100. Reason is that scaling up all attributes of the rectangle separately can lead to rounding errors. Scaling them together as a rectangle solves this limitation.

[github-actions]

Test Results

   494 files  ±0     494 suites  ±0   8m 28s ⏱️ -53s
 4 332 tests +1   4 319 ✅ +1   13 💤 ±0  0 ❌ ±0 
16 573 runs  +1  16 465 ✅ +1  108 💤 ±0  0 ❌ ±0 

Results for commit 3cc2e94. ± Comparison against base commit 56767ec.

[HeikoKlare]

This is part of completing a fix in 2016 (3b55f60) improving the initial HiDPI support (e02d49a) for fractional scale values, which was only applied to according calculations in DPIUtil but not to all consumers that contained the same inaccuracy.