fix(canvas_text_bbox_calculator): increase font scaling factor

[emmacunningham]

Summary

close #90

This PR fixes the truncation issues with formatted labels on Chrome by adding a 1px padding amount to cover any undercalculation. This also means that we can now significantly reduce the amount that we are scaling fonts by. It does not completely remove the need for a bit of scaling (tested just with offsetting with padding and there was still some truncation).

On Mac OS X Chrome:

Also, see #94 for enhancing this by allowing users to define more padding.

Checklist

Use strikethroughs to remove checklist items you don't feel are applicable to this PR.

• This was checked for cross-browser compatibility, including a check against IE11
  - [ ] Proper documentation or storybook story was added for features that require explanation or tutorials
  - [ ] Unit tests were updated or added to match the most common scenarios
• Each commit follows the convention

[codecov-io]

Codecov Report

Merging #93 into master will increase coverage by 0.44%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #93      +/-   ##
==========================================
+ Coverage   88.07%   88.51%   +0.44%     
==========================================
  Files          28       28              
  Lines        1132     1132              
  Branches      118      118              
==========================================
+ Hits          997     1002       +5     
+ Misses        125      120       -5     
  Partials       10       10

Impacted Files	Coverage Δ
src/lib/axes/canvas_text_bbox_calculator.ts	100% <100%> (+31.25%)	⬆️

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[emmacunningham]

@markov00 Codecov was blocking merge because we didn't have any tests written for canvas_text_bbox_calculator, so I went to write those tests to get this through, but then it turned out to be a bit more involved since we needed to add support for mocking canvas in our jest tests for all of the functionality to be tested :) Let me know if you prefer to have the updated tests in a different PR and keep this one just focused on the fixes for the text truncation and I can move these commits to another PR.

[markov00]

Awesome, Code looks good to me and tested locally on chrome works fine.
I've also see that you already added the canvas mock and solved the testing so ok to merge

[markov00]

🎉 This PR is included in version 3.0.1 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

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