buildhistory: Fix package output files for SDKs

Currently, installed packages are listed for images in image-info.txt, but
not for SDKs in sdk-info.txt. Add TOOLCHAIN_HOST_TASK and
TOOLCHAIN_TARGET_TASK to the output variables in sdk-info.txt.

Moreover, package output files for the SDK host are empty because
PKGDATA_DIR defaults to the target directory. Fix this bug and create a new
variable called PKGDATA_DIR_SDK which stores the correct path for the SDK
host package data.

Signed-off-by: Andres Beltran <abeltran@linux.microsoft.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>