Remove trait CtxMethods - work towards #11474

[nielsle]

Remove the trait CtxMethods and convert all methods to functions. The diff is a little hard to read, but I tried to do very little apart from indenting and editing the lines containing "fn"

[alexcrichton]

Why was this change done? This is backwards in terms of style with the rest of the compiler? Having a "context" with methods hung of it is incredibly frequent, why change them all to global functions?

[nielsle]

The next step is to move all the functions to a separate crate name run_cmd and turn them in to private functions. That will make them encapsulated again. This will happen in next PR.

The overall goal is to remove the dependence on BuildContext. Therefore I wanted to start out removing the trait named CtxMethods that was implemented by BuildContext.

Subsequently I want to remove build_context as a parameter to some of the functions. So in the long run you will be able to run "ruspkg info" without creating a build_context with a work_cache.

EDIT: As I see it the build_context should not be created before rustpkg has decided that the user wants to build or install. This should happen after rustpkg has validated the command line. If you disagree with this, then my changes should probably be reverted.

[nielsle]

After discussing on irc. I retract this PR.