feat: allowed hydration directory to be empty

[JoshuaKGoldberg]

PR Checklist

• Addresses an existing open issue: fixes 🚀 Feature: Allow hydration/migration to run on an empty directory #669
• That issue was marked as status: accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

Changes split out of #668:

• If git status fails, runs git init to make the directory a repo
• Allows package.json to be empty, defaulting its contents to {}

[codecov]

Codecov Report

Merging #673 (3cf6331) into main (7cba114) will increase coverage by 0.38%.
Report is 3 commits behind head on main.
The diff coverage is 75.00%.

@@            Coverage Diff             @@
##             main     #673      +/-   ##
==========================================
+ Coverage   49.87%   50.25%   +0.38%     
==========================================
  Files          63       64       +1     
  Lines         389      396       +7     
  Branches       75       76       +1     
==========================================
+ Hits          194      199       +5     
- Misses        185      186       +1     
- Partials       10       11       +1     

Flag	Coverage Δ
hydrate	100.00% <ø> (ø)
setup	∅ <ø> (∅)
unit	49.74% <75.00%> (+0.39%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
src/hydrate/index.ts	0.00% <ø> (ø)
src/hydrate/steps/finalizeDependencies.ts	100.00% <ø> (ø)
...hydrate/steps/writing/creation/writePackageJson.ts	88.88% <0.00%> (-11.12%)	⬇️
src/setup/steps/updateAllContributorsTable.ts	0.00% <0.00%> (ø)
src/shared/getDefaultSettings.ts	100.00% <ø> (ø)
src/shared/ensureGitRepository.ts	100.00% <100.00%> (ø)
src/shared/runOrRestore.ts	88.88% <100.00%> (+0.31%)	⬆️

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[github-actions]

🎉 This is included in version v1.28.56 🎉

The release is available on:

• GitHub releases
• npm package (@latest dist-tag)

Cheers! 📦🚀