pseq: Create standalone config file parser

Create a standalone JSON configuration file parser for the
phosphor-power-sequencer application.  Support the new config file
properties in the parser.

Separating the config file parser from the rest of the code makes it
easier to implement and test.

Create automated test cases to verify the parser functions.

Change-Id: Ia753ffadf395359899964a612e479b00377ad495
Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
diff --git a/phosphor-power-sequencer/test/meson.build b/phosphor-power-sequencer/test/meson.build
index ab03041..4f6b167 100644
--- a/phosphor-power-sequencer/test/meson.build
+++ b/phosphor-power-sequencer/test/meson.build
@@ -1,5 +1,7 @@
 test('phosphor-power-sequencer-tests',
      executable('phosphor-power-sequencer-tests',
+                'config_file_parser_error_tests.cpp',
+                'config_file_parser_tests.cpp',
                 'rail_tests.cpp',
                 dependencies: [
                     gtest,
@@ -7,10 +9,15 @@
                 ],
                 link_args: dynamic_linker,
                 build_rpath: get_option('oe-sdk').allowed() ? rpath : '',
+                link_with: [
+                    phosphor_power_sequencer_library,
+                    libpower
+                ],
                 implicit_include_directories: false,
                 include_directories: [
                     '.',
-                    '../src'
+                    '../src',
+                    '../..'
                 ]
      )
 )