[ENH] Add PDF format to image exporters

[ales-erjavec]

Issue

Add PDF format to image exporters

Description of changes

Includes

• Code changes
• Tests
• Documentation

[astaric]

I get the following error on Windows:

Cannot open file 'C:\Users\x\AppData\Local\Temp\tmpo3q1_c1y.svg', because: The process cannot access the file because it is being used by another process.

[codecov-io]

Codecov Report

Merging #2210 into master will decrease coverage by 0.05%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #2210      +/-   ##
==========================================
- Coverage   72.17%   72.11%   -0.06%     
==========================================
  Files         318      318              
  Lines       54765    54711      -54     
==========================================
- Hits        39526    39457      -69     
- Misses      15239    15254      +15

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