feat: add region check

[sa7mon]

Changes

• Add regioncheck cmd. This cmd is to be run periodically and for each provider that requires a client-per-region will:
  • make a request to the provider's documentation site or meta API to get a list of all available regions
  • compare that list of regions against the static list in provider/providers.go
  • if the lists differ, print the difference and exit with a code of 1
• Add workflow to run the cmd on each PR. In the future, this may be changed to run on a regular schedule.

Closes #152

[github-actions]

Package	Line Rate	Complexity	Health
github.com/sa7mon/s3scanner/bucket	90%	0	✔
github.com/sa7mon/s3scanner/cmd/regioncheck	57%	0	➖
github.com/sa7mon/s3scanner/cmd/s3scanner	19%	0	❌
github.com/sa7mon/s3scanner/db	73%	0	➖
github.com/sa7mon/s3scanner/permission	77%	0	✔
github.com/sa7mon/s3scanner/provider	81%	0	✔
github.com/sa7mon/s3scanner/worker	49%	0	❌
Summary	64% (532 / 832)	0	➖