refactor: use fs.promises in cli/run, Part 1

[dnalborczyk]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers:

Description

[codecov]

Codecov Report

Merging #4371 (de0b23a) into master (5364114) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #4371   +/-   ##
=======================================
  Coverage   98.70%   98.70%           
=======================================
  Files         205      205           
  Lines        7320     7320           
  Branches     2083     2083           
=======================================
  Hits         7225     7225           
  Misses         35       35           
  Partials       60       60           

Impacted Files	Coverage Δ
cli/run/getConfigPath.ts	88.88% <100.00%> (ø)
cli/run/index.ts	100.00% <100.00%> (ø)
cli/run/loadConfigFile.ts	96.15% <100.00%> (ø)
cli/run/watch-cli.ts	89.70% <100.00%> (ø)

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