staging: Save out provider information into the sysroot
This patch saves out provider information into the sysroot for all providers
except those in MULTI_PROVIDER_WHITELIST. This means that we will start seeing
warnings when two providers for the same thing are installed into the sysroot.
In the future those warnings can be turned into errors.
Partially addresses [YOCTO #4102]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
