style: run prettier on all files

[ripecosta]

Why am I submitting this PR

Quality of life improvement that extends the Prettier config so it runs on all files in the repo. Also adds a .editorconfig file that configures file formats for both Prettier (docs) and modern IDEs.

Does it fix an existing ticket?

No.

Checklist

• [x] only relevant code is changed (make a diff before you submit the PR)
• [x] tests are included and pass: yarn test (see details here)
• [x] documentation is changed or added

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 95.35%. Comparing base (168c8d5) to head (72200f2). Report is 57 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1047 +/- ## ========================================== - Coverage 95.40% 95.35% -0.05% ========================================== Files 11 10 -1 Lines 1937 1918 -19 ========================================== - Hits 1848 1829 -19 Misses 89 89 ```

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