Cherry-pick fixes (line height unit change preserves line height, gaussian blur widget initialization, cursor opacity)

Continuation of !3636 (merged)

Will need to do some testing but running the pipeline first...

By commit (latest commit first):

1. d0fb7fb8 Fixes cursors with transparent stroke/fill colors #2025 (closed) !3575 (merged)
2. 6a878ab7 Fix Gaussian Blur value in Filter Editor !3577 (merged) #2724 (closed) The 'Standard Deviation' for the blur now displays as 0 when drop shadow has 0 blur.
3. 471edd21 Stop changing line height when units change !3544 (merged) #2465 (closed)