Addl test for validation across files

Add new tests that ensure that validation across files and involving
multiple macro/rule objects display the right context. When appending,
both objects are displayed. When overwriting, the overwritten object is
displayed.

Signed-off-by: Mark Stemm <mark.stemm@gmail.com>

test/rules/invalid_append_macro.yaml

@@ -0,0 +1,3 @@
+- macro: some macro
+  condition: foo
+  append: true

test/rules/invalid_append_rule.yaml

@@ -0,0 +1,6 @@
+- rule: some rule
+  desc: some desc
+  condition: bar
+  output: some output
+  priority: INFO
+  append: true

test/rules/invalid_base_macro.yaml

@@ -0,0 +1,2 @@
+- macro: some macro
+  condition: evt.type=execve

test/rules/invalid_base_rule.yaml

@@ -0,0 +1,5 @@
+- rule: some rule
+  desc: some desc
+  condition: evt.type=open
+  output: some output
+  priority: INFO

test/rules/invalid_overwrite_macro.yaml

@@ -0,0 +1,3 @@
+- macro: some macro
+  condition: foo
+  append: false

test/rules/invalid_overwrite_rule.yaml

@@ -0,0 +1,6 @@
+- rule: some rule
+  desc: some desc
+  condition: bar
+  output: some output
+  priority: INFO
+  append: false