containers: introduce sloci for generating OCI image directories

There are multiple different tools/techniques to generate OCI images.
Many of these techniques are part of more complex workflows, or have
many options that are needed as part of a larger system or are needed
to provide flexibility in the tooling (i.e. they construct the
container as well as build the OCI image, or they can push directly
to a registry, etc).

What we want within the build context of bitbake/oe is to not
duplicate work that is done by bitbake, the other image bbclasses
or the runtime part of the ecosystem. This means only the construction
of an image-spec v1.x image without dependencies on build, or execution
of the container within a tool. We'd also like the tool to not pull
in multiple, unused dependencies that must be built native/native-sdk,
etc, to support the simple use case.

The requirements above exclude (for now) tools such as skopeo, umoci,
buildah, img, orca-build, kaniko, scratchbuild, etc. Leading us to
a from-scratch implementation .. or enter sloci-image.

sloci-image is a simple CLI for packing a rootfs into a single layer
OCI image. It can easily be extended, or ported to other language
implementations in the future. But it brings nearly no native
dependencies and is a pure/clean implementation of the image spec
that integrates nicely in an oe/bitbake environment.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

recipes-containers/sloci-image/sloci-image-native_git.bb

@@ -0,0 +1,22 @@
+SUMMARY = "A simple CLI tool for packing rootfs into a single-layer OCI image"
+LICENSE = "MIT"
+LIC_FILES_CHKSUM = "file://git/LICENSE;md5=948cd8e59069fad992b0469af9ad7966"
+SRC_URI = "git://github.com/jirutka/sloci-image.git"
+
+DEPENDS = ""
+
+SRCREV = "4015e49763e5a738026a5bbfcf32b38b5a4fa650"
+PV = "v0.1.0+git${SRCPV}"
+
+inherit native
+
+S = "${WORKDIR}"
+
+do_compile() { 
+	:
+}
+
+do_install() {
+	cd ${S}/git
+        make PREFIX="${exec_prefix}" DESTDIR=${D} install
+}