[EPIC] PulumiTest GA

[danielrbradley]

Providers has developed a new testing framework called pulumitest on top of automation API that is a lot more flexible than ProgramTest. We should promote this as a better tool for our community to test pulumi. (We could continue to support Programtest by implementing on top of pulumitest.)

Must Have

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1. Move into own standalone library instead of being a module inside of providertest
2. pulumitest: Add local python SDK replacement option #39
   kind/enhancement +1
3. pulumitest: edit SDK dependency #40
   kind/enhancement +1
4. Write blog post on testing
5. Secret scrubbing should maintain JSON schema #108
   kind/bug resolution/fixed security +3
   
6. Make failed test cleanup easier #109
   kind/enhancement resolution/fixed +2
   

Should Have

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1. Add more docs to include real-world examples of usage
2. Stop capturing testing.T instance #104
   kind/enhancement resolution/fixed +2
   

Could Have

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1. Support inline yaml programs #99
   kind/enhancement +1