libsnapshot_cow: Create snapshot patch for full OTA

create_snapshot --target=$ANDROID_PRODUCT_OUT/product.img --compression="zstd"
Snapshot patch: product.patch created successfully

Snapshot patch: product.patch created successfully
$ ls -lh product.patch
-rw-r--r-- 1 akailash primarygroup 1.8G Sep 17 22:21 product.patch

Default compression set to lz4.

Bug: 299011882
Test: create_snapshot --target=$ANDROID_PRODUCT_OUT/product.img --compression="zstd"
Change-Id: I42845ccf5d55fddd2bdfc7dae92510d247bb71e6
Signed-off-by: Akilesh Kailash <akailash@google.com>