Add HT enum in Interop User32

[gpetrou]

Proposed changes

• Add HT enum in Interop User32.
• Remove HT constants and replace their usages with the above enum values.

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

Merging #2836 into master will decrease coverage by 0.01966%.
The diff coverage is 4.7619%.

@@                 Coverage Diff                 @@
##              master       #2836         +/-   ##
===================================================
- Coverage   59.45618%   59.43652%   -0.01966%     
===================================================
  Files           1236        1236                 
  Lines         429518      429512          -6     
  Branches       38778       38778                 
===================================================
- Hits          255375      255287         -88     
- Misses        168787      168856         +69     
- Partials        5356        5369         +13

Flag	Coverage Δ
#Debug	59.43652% <4.7619%> (-0.01967%)	⬇️
#production	32.13879% <4.7619%> (-0.03388%)	⬇️
#test	98.96944% <ø> (ø)	⬆️

[RussKie]

👍 with few questions