Retry with exponential backoff for stream opening

[aarshkshah1992]

Closes filecoin-project/lotus#3416.

@hannahhoward Should we do this for the retrieval market as well ?

[hannahhoward]

LGTM. Yes, let's do this for retrieval as well.

[hannahhoward]

make sure to fix lint errors before merge

[hannahhoward]

Hey @aarshkshah1992 -- I'm getting a freeze in the tests when I rebased on master after merging your other PR (the restart testing). Can you rebase on master and investigate?

[aarshkshah1992]

@hannahhoward On it.

[aarshkshah1992]

@hannahhoward

1. There was a very deep bug in the test wherein because of using randomly generated temporary file paths, we weren't being to find the piece file across restarts. Because of this, the provider failed when trying to do a HandoffDeal on the restart. Have fixed that bug now and the tests look good on repeated runs.

2. Have added the backoff-retry logic for the retrieval markets as well.

[hannahhoward]

@aarshkshah1992 this great but it looks like you still have lint and test failures. At least one of the test failures looks non-flaky and needs a change. (TestProviderStop)

[aarshkshah1992]

@hannahhoward Fixed the linting issue and test. Please take a look. The other failures are flakies for which I've created an issue.