[tradefed] Add local download support

[axelnxp]

It would be nice to be able to get the archive from a local storage, instead of a HTTP server.

[mwasilew]

@axelnxp I assume you refer to the CTS zip file. This is specific to the test-definition for tradefed which uploads the zip file to the archive server. So it makes sense in this case. I'm not sure how would that work in the case you're asking for.