rust: Move cargo config options into environment variables

rust: Move cargo config options into environment variables

This also:

* Modify the "release" profile in place of adding the "stripped" profile

  Only the profile for target is modified; there are no file size
  constraints for host.

* For host, build with the "release" profile

* For target, build with either the "dev" or "release" profile based on
  CONFIG_DEBUG

There is no environment variable to specify the "strip" option, but
enabling this option is not necessary as the build system will already
strip binaries based on CONFIG_NO_STRIP / CONFIG_USE_STRIP /
CONFIG_USE_SSTRIP.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>