Add a flag to enable/disable analytics so uplink can be run
non-interactively. Also when run non-interactively for the first time
it will not error any more but instead default to disable analytics.
Part of https://github.com/storj/storj/issues/5126
Change-Id: I07ac8a040664334efcb4e2536f26c330c1751a6f
As a reminder: latest clingy removed the requirement of having custom context (which made the usage of context.WithValue harder) and uses simple context instead.
Clingy saves the stdin/stdout/stderr to the context (earlier to separated context type) to make it available for unit testing.
Change-Id: I8896574f4670721de43a577cd4b35952e3b5d00e
