VEditorKit: Define default caret rect using with style.minHeight

[GeekTree0101]

Why need this change?:

• Empty Text View Caret size is too small & unmatched with default typing paragraph lineheight

Change made & impact:

• Setup style minimum height

Test Scope:

• minimumTextContainerTextLineHeight() should be return expected height

Vertified snapshots (optional)

[codecov-io]

Codecov Report

Merging #52 into master will increase coverage by 0.03%.
The diff coverage is 80%.

@@            Coverage Diff             @@
##           master      #52      +/-   ##
==========================================
+ Coverage   67.01%   67.04%   +0.03%     
==========================================
  Files          25       25              
  Lines        1737     1742       +5     
==========================================
+ Hits         1164     1168       +4     
- Misses        573      574       +1

[OhKanghoon]

Looks good