regulators: Add phase faults to ActionEnvironment

Enhance the ActionEnvironment class to support detecting and logging
redundant phase fault errors.

Add gtests to test the new functions/methods.

Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
Change-Id: Id87d811374dd3da616cdeeb780b3575ef96ffbb7
diff --git a/phosphor-regulators/test/meson.build b/phosphor-regulators/test/meson.build
index 3f16812..897e540 100644
--- a/phosphor-regulators/test/meson.build
+++ b/phosphor-regulators/test/meson.build
@@ -14,6 +14,7 @@
     'exception_utils_tests.cpp',
     'ffdc_file_tests.cpp',
     'id_map_tests.cpp',
+    'phase_fault_tests.cpp',
     'pmbus_error_tests.cpp',
     'pmbus_utils_tests.cpp',
     'presence_detection_tests.cpp',