feat: focus next item when the user finished to edit style value

[ktsn]

ref #13

By this PR, the focus on style input form will move the next item when the user finishes to edit it by pressing enter or tab key.

[codecov]

Codecov Report

Merging #71 into master will increase coverage by 0.61%.
The diff coverage is 87.5%.

@@            Coverage Diff             @@
##           master      #71      +/-   ##
==========================================
+ Coverage   67.42%   68.04%   +0.61%     
==========================================
  Files          66       66              
  Lines        2229     2244      +15     
  Branches      455      461       +6     
==========================================
+ Hits         1503     1527      +24     
+ Misses        706      697       -9     
  Partials       20       20

Impacted Files	Coverage Δ
src/view/components/StyleValue.vue	46.66% <100%> (+2.8%)	⬆️
src/view/components/StyleDeclaration.vue	93.33% <66.66%> (-6.67%)	⬇️
src/view/components/StyleInformation.vue	65.62% <85.71%> (+65.62%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2f33c62...396ae13. Read the comment docs.