fix: extralines bugs

[ChrGrb]

fixes #1425

Changes

• Added top padding to calculation of lower boundary of VerticalLineLabel, to make label actually be pushed down if top padding is added
• Added bottom padding to calculation for upper boundary of HorizontalLineLabel, to make label actually be pushed up if bottom padding is added
• Changed full canvas to be restored before extra line is drawn, in case it was clipped before, and to be clipped again afterwards

[docs-page]

To view this pull requests documentation preview, visit the following URL:

docs.page/imanneo/fl_chart~1426

Documentation is deployed and generated using docs.page.

[codecov]

Codecov Report

Merging #1426 (13684b8) into master (ce49b92) will decrease coverage by 0.02%.
Report is 7 commits behind head on master.
The diff coverage is 81.25%.

❗ Current head 13684b8 differs from pull request most recent head ca0dc80. Consider uploading reports for the commit ca0dc80 to get more accurate results

@@            Coverage Diff             @@
##           master    #1426      +/-   ##
==========================================
- Coverage   86.48%   86.47%   -0.02%     
==========================================
  Files          45       45              
  Lines        2982     2986       +4     
==========================================
+ Hits         2579     2582       +3     
- Misses        403      404       +1     

Files	Coverage Δ
lib/src/chart/line_chart/line_chart_painter.dart	91.82% <92.85%> (-0.13%)	⬇️
.../src/chart/base/axis_chart/axis_chart_painter.dart	72.76% <0.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[imaNNeo]

Can you please rebase your branch?

[imaNNeo]

I think you need to rebase your branch.