Add a home page

[danielemery]

• Gives some basic information about the instance
  • It's name - (a new option)
  • The number of loaded ssh keys
  • The number of loaded PGP keys
  • The version the instance is running
• Plain text only (html and json still reserved to be done in Support html content type #34 and Support json content type #33 respectively)

[codecov]

Codecov Report

Attention: Patch coverage is 90.38462% with 5 lines in your changes missing coverage. Please review.

Project coverage is 93.64%. Comparing base (4caf8da) to head (b9ba528).
Report is 3 commits behind head on main.

Files	Patch %	Lines
src/test_helpers.ts	64.28%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #54      +/-   ##
==========================================
- Coverage   94.23%   93.64%   -0.60%     
==========================================
  Files           9       11       +2     
  Lines         295      346      +51     
  Branches       42       44       +2     
==========================================
+ Hits          278      324      +46     
- Misses         17       22       +5     

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