feat(barchart) set custom text value in the bar

[karthago1]

Hello again 😸

somehow I missed this feature, while integrating the new code. (In my original PR #288, I had a function pointer, which formats the values. format: fn(u64) -> String).

This patch suggests adding a new function text_value to the Bar, which will override the default text value

Bar::default()
     .label("Temperature".into())
     .value(10)
     .text_value("10°C".to_string());

Commit message:

for now the value is converted to a string and then printed. in many cases the values are too wide or double values. so it make sense to set a custom value text instead of the default behavior.

this patch suggests to add a method fn text_value(mut self, text_value: String) to the Bar, which allows to override the value printed in the bar

[codecov]

Codecov Report

Merging #309 (7d0acaa) into main (2889c7d) will decrease coverage by 0.05%.
The diff coverage is 100.00%.

❗ Current head 7d0acaa differs from pull request most recent head 0e82d47. Consider uploading reports for the commit 0e82d47 to get more accurate results

@@            Coverage Diff             @@
##             main     #309      +/-   ##
==========================================
- Coverage   83.85%   83.81%   -0.05%     
==========================================
  Files          38       38              
  Lines        8045     8036       -9     
==========================================
- Hits         6746     6735      -11     
- Misses       1299     1301       +2     

Impacted Files	Coverage Δ
src/widgets/barchart/bar.rs	100.00% <100.00%> (ø)
src/widgets/barchart/mod.rs	89.35% <100.00%> (-0.02%)	⬇️

... and 1 file with indirect coverage changes

[joshka]

@karthago1 to make it easier to merge in the future, can you please enable signing commits?
See https://docs.github.com/articles/about-gpg/ for more info

[joshka]

LGTM. Thanks again!