Refactor build process, fix helm chart, use mongo-tools, cleanup on fail

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This PR

• adds a simple feature to clean up partial dumps from the temp folder to save some space
• updates base image tools:
  • alpine 3.14
  • mongodb tools 100.5.1 (compatible with a great range of mongo versions, from 4.0 to 5.0)
  • gnupg 2.2.31-r0
  • google cloud sdk 370.0.0
  • azure cli 2.32.0
  • aws-cli 1.22.46
• options to enable or disable different cloud storage engines
• turn the chart back to alpine, to keep the image smaller
• completely refactored docker image build to enable to build cloud specific versions (images: https://hub.docker.com/r/endrec/mgob/tags)

This PR incorporates #148, which in turn includes #128 and #139, which fixes a bug introduced in #135 (h flag is reserved).

Fixes #123

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@stefanprodan I know you are not working with mongodb any more, so I'm not sure it even worth sending PR, but as this used to be the home of mgob for years, I believe this is still the best place to add these changes.

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We switched to Debian recently because Alpine was missing some Mongo packages. I can't tell if the new image works, maybe you can confirm that this was tested?

Yep, works nicely, runs on my test cluster for a day now, creating a backup every half an hour like clockwork. 😄

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Thanks for the super quick merge, @stefanprodan !