test: spl: Add functions to create images

This add some basic functions to create images, and a test for said
functions. This is not intended to be a test of the image parsing
functions, but rather a framework for creating minimal images for testing
load methods. That said, it does do an OK job at finding bugs in the image
parsing directly.

Since we have two methods for loading/parsing FIT images, add LOAD_FIT_FULL
as a separate CI run.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/sandbox_spl_defconfig b/configs/sandbox_spl_defconfig
index 4a67af2..b578cc8 100644
--- a/configs/sandbox_spl_defconfig
+++ b/configs/sandbox_spl_defconfig
@@ -32,6 +32,12 @@
 CONFIG_SPL_NO_BSS_LIMIT=y
 CONFIG_HANDOFF=y
 CONFIG_SPL_BOARD_INIT=y
+CONFIG_SPL_LEGACY_IMAGE_FORMAT=y
+CONFIG_SPL_LOAD_IMX_CONTAINER=y
+CONFIG_SPL_SYS_MALLOC=y
+CONFIG_SPL_HAS_CUSTOM_MALLOC_START=y
+CONFIG_SPL_CUSTOM_SYS_MALLOC_ADDR=0xa000000
+CONFIG_SPL_SYS_MALLOC_SIZE=0x4000000
 CONFIG_SPL_ENV_SUPPORT=y
 CONFIG_SPL_FPGA=y
 CONFIG_SPL_I2C=y