addons/namingng.py: Add tests for include guards, config file validat…

…ion. (#5815)

Include guard naming can be validated against various patterns:
- prefixes/suffixes (`_FILE_H`, `PROJECT_FILE_H`, `FILE_H_`)
- basename/full path (`FILE_H`, `SUB_DIR_INC_FILE_H`)
- upper- or lowercase (`FILE_H`, `file_h`)
- any combination of the above (`project_sub_dir_inc_file_h_`)

A regexp can be specified to match header filenames. The example matches
any filename not starting with / and ending with `.h`, intended to match
C header files while exluding system files.

The test is not limited to naming only; validity and presence of include
guards can also be tested by setting `"required":true` in the config
file.

Enabling this feature requires adding the key `"include_guard"` to the
namingng config file used.

The namingng unit test is extended to test various features of the
include guard test.

Also, config handling is improved, adding (superficial) validation and a
unit test.

addons/namingng.config.json

@@ -2,6 +2,15 @@
     "RE_VARNAME": ["[a-z]*[a-zA-Z0-9_]*\\Z"],
     "RE_PRIVATE_MEMBER_VARIABLE": null,
     "RE_FUNCTIONNAME": ["[a-z0-9A-Z]*\\Z"],
+    "include_guard": {
+        "input": "path",
+        "prefix": "",
+        "suffix": "",
+        "case": "upper",
+        "max_linenr": 5,
+        "RE_HEADERFILE": "[^/].*\\.h\\Z",
+        "required": true
+    },
     "var_prefixes": {"uint32_t": "ui32",
                      "int*": "intp"},
     "function_prefixes": {"uint16_t": "ui16",