Add runtime.Runtime to hold config, DB and S3

[rowanseymour]

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[codecov]

Codecov Report

Attention: Patch coverage is 83.11688% with 13 lines in your changes missing coverage. Please review.

Project coverage is 63.34%. Comparing base (1b82d85) to head (58cc7b8).

Files	Patch %	Lines
cmd/rp-archiver/main.go	0.00%	10 Missing ⚠️
archives/runs.go	77.77%	1 Missing and 1 partial ⚠️
archives/messages.go	88.88%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #104      +/-   ##
==========================================
- Coverage   63.40%   63.34%   -0.07%     
==========================================
  Files           7        7              
  Lines        1003     1004       +1     
==========================================
  Hits          636      636              
- Misses        262      263       +1     
  Partials      105      105              

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