Allow arbitrary indent characters for developers

[lorenzwalthert]

Closes #874

[github-actions]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if 8f3c615 is merged into main:

•   :ballot_box_with_check:cache_applying: 27.8ms -> 27.9ms [-2.94%, +3.48%]
•   :ballot_box_with_check:cache_recording: 1.31s -> 1.3s [-2.45%, +0.91%]
•   :ballot_box_with_check:without_cache: 3.46s -> 3.45s [-1.54%, +1.15%]

Further explanation regarding interpretation and methodology can be found in the documentation.

[github-actions]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if effc7d6 is merged into main:

•   :ballot_box_with_check:cache_applying: 24.2ms -> 24.3ms [-0.19%, +1.06%]
•   :ballot_box_with_check:cache_recording: 986ms -> 978ms [-3.24%, +1.61%]
•   :ballot_box_with_check:without_cache: 2.72s -> 2.71s [-0.86%, +0.23%]

Further explanation regarding interpretation and methodology can be found in the documentation.

[codecov-commenter]

Codecov Report

Merging #916 (e623d4b) into main (fd466c1) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #916      +/-   ##
==========================================
+ Coverage   90.38%   90.44%   +0.05%     
==========================================
  Files          47       47              
  Lines        2559     2574      +15     
==========================================
+ Hits         2313     2328      +15     
  Misses        246      246              

Impacted Files	Coverage Δ
R/serialize.R	100.00% <100.00%> (ø)
R/style-guides.R	99.41% <100.00%> (+0.02%)	⬆️
R/testing.R	79.85% <100.00%> (+0.29%)	⬆️
R/transform-block.R	100.00% <100.00%> (ø)

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[github-actions]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if 6777efa is merged into main:

•   :ballot_box_with_check:cache_applying: 27.8ms -> 28.2ms [-2.3%, +5.36%]
•   :ballot_box_with_check:cache_recording: 1.18s -> 1.18s [-0.8%, +1.35%]
•   :ballot_box_with_check:without_cache: 3.13s -> 3.12s [-1.72%, +1.12%]

Further explanation regarding interpretation and methodology can be found in the documentation.