UI: Make projector display resolutions DPI-aware

Follow up to PR #3988 and commit
5cdd084c7f.
Without this change, displays listed as projector targets on systems
using a fractional scaling factor (e.g., 125%, 150%, 175%) will show an
incorrect width and height for their size. For a display with 125%
scaling, OBS would show 1536x864 instead of 1920x1080. With this change,
it will show 1920x1080.
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f