Postpone all changes to renpy until build succeeds

[Andykl]

Currently build tasks modify mounted renpy in tasks right away. This creates 2 problems

1. If build fails, state of lib, rapt and renios is undefined.
2. In devcontainer on Windows there is a race for e.g.

    c.run("install -d {{ dlpa }}")
    c.run("install {{ prebuilt }}/{{ c.arch}}/libGLESv2.dll {{ dlpa }}")

where if host directory was not created in time second install is run as if dlpa is also install target, not a directory install to and fails.

I think it is better to first install things into tmp/install/... on the same filesystem and then copy the result as a whole as last task.

[renpytom]

I don't have too much of a problem with this, though it might make sense to only copy directories that correspond to platform-arch pairs that have been compiled.

[Andykl]

Yeah, that make sense. Will also skip rapt/renios when not building Android/ios because right now it leaves them broken without compiled libraries.