Exclude file list for xen-analysis script

The code analysis is performed on the Xen codebase for both MISRA checkers and static analysis checkers, there are some files however that needs to be removed from the findings report for various reasons (e.g. they are imported from external sources, they generate too many false positive results, etc.).

For this reason the file docs/misra/exclude-list.json is used to exclude every entry listed in that file from the final report. Currently only the cppcheck analysis will use this file.

Here is an example of the exclude-list.json file:

|    "version": "1.0",
|    "content": [
|        {
|            "rel_path": "relative/path/from/xen/file",
|            "comment": "This file is originated from ..."
|        },
|        {
|            "rel_path": "relative/path/from/xen/folder/*",
|            "comment": "This folder is a library"
|        },
|        {
|            "rel_path": "relative/path/from/xen/mem*.c",
|            "comment": "memcpy.c, memory.c and memcmp.c are from the outside"
|        }
|    ]
Here is an explanation of the fields inside an object of the "content" array:

To ease the review and the modifications of the entries, they shall be listed in alphabetical order referring to the rel_path field. Excluded folder paths shall end with '/*' in order to match everything on that folder.