Fix BarChart isn't fit to the visibility of its

[sownt]

It's cause of minY value from BarChartHelper always 0.0 if any fromY of BarChartData is positive. So min value of Y-axis always starts from 0.0 or a negative value.

I update minY value of chart to min of fromY any values of ChartData. This is result of my change, Line 1 will be hide and Y-axis will start from 150.

I also update bar_chart_painter_test for its.

[codecov]

Codecov Report

Merging #1387 (5a06f90) into master (478e5e6) will increase coverage by 0.43%.
Report is 9 commits behind head on master.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1387      +/-   ##
==========================================
+ Coverage   86.09%   86.52%   +0.43%     
==========================================
  Files          45       45              
  Lines        2978     2984       +6     
==========================================
+ Hits         2564     2582      +18     
+ Misses        414      402      -12     

Files Changed	Coverage Δ
lib/src/chart/bar_chart/bar_chart_helper.dart	97.14% <100.00%> (+0.26%)	⬆️
lib/src/chart/bar_chart/bar_chart_painter.dart	96.12% <100.00%> (+3.94%)	⬆️

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[imaNNeo]

I did some changes to this (merged) MR
Please check the master branch and let me know what do you think about it.