jiri: Add more helper methods to profiles and runutil.

profile gets Fetch and Unzip methods.  These have TODOs to move to a
packages for profile implementors once it exists.

runutil gets Create, Copy, OpenFile, and TempFile.

These functions are needed by the mojo profile (coming soon).

Change-Id: I78c4638a254f036ec2d5e89a55849df401079066
2 files changed