Add custom fonts

[johnfercher]

Description

• Remove gomnd linter about magic numbers since we deal with algebric and color values
• Add custom UTF8 fonts
• Change color usage to pointers
• Add docs (https://maroto.io/#/v2/features/customfont?id=custom-font)
• Add color to default font
• Remove font from config, using props instead.
• Remove TableList code
• MakeValid now uses font instead of only font family

Related Issue

Checklist

check with "x", if applied to your change

• All methods associated with structs has func (s *struct) method() {} name style.
• Wrote unit tests for new/changed features.
• Updated docs/doc.go
• Updated pkg/pdf/example_test.go
• Updated README.md
• Updated all examples inside internal/examples
• New public methods/structs/interfaces has comments upside them explaining they responsibilities
• Executed make dod with none issues pointed out by golangci-lint and goreportcard-cli

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (v2@df59518). Click here to learn what that means.
Patch has no changes to coverable lines.

Additional details and impacted files

@@          Coverage Diff          @@
##             v2     #293   +/-   ##
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  Coverage      ?   31.82%           
=====================================
  Files         ?       15           
  Lines         ?      789           
  Branches      ?        0           
=====================================
  Hits          ?      251           
  Misses        ?      534           
  Partials      ?        4           

Flag	Coverage Δ
unittests	31.82% <0.00%> (?)

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