test: add top level unit test suite

This currently includes cli-pretty tests. It could be executed
separately to clarify test results in github actions. This commit
includes it in the main test execution. The most important thing is
that it's executed.

Signed-off-by: Richard Alpe <richard@bit42.se>

board/x86_64/board.mk

@@ -1,5 +1,5 @@
 test-dir := $(BR2_EXTERNAL_INFIX_PATH)/test
-INFIX_TESTS ?= $(test-dir)/case/all.yaml
+INFIX_TESTS ?= $(test-dir)/case/all-unit.yaml $(test-dir)/case/all.yaml
 
 test-env = $(test-dir)/env \
 	-f $(BINARIES_DIR)/infix-x86_64.img \

test/case/all-unit.yaml

@@ -0,0 +1,5 @@
+---
+# Tests in this suite can be run on localhost without a target environment
+
+- name:  cli-pretty
+  suite: cli_pretty/all.yaml