fix: Tools for reformatting code. (GIT8266O-364)

[trygvis]

Hi

It would be if this project had a more consistent code style. I suggest using clang-format, it seems to be quite flexible, maintained, well documented and popular in other big projects. I've added a .clang-format file that is quite close to the current style (but the current style is a bit all over the place).

I've made a small tool that will replace tabs with 4 spaces and run clang-format on the source code. File patterns are configurable with a gitignore style file.

The commit message contains more information, but the also see README.md.

This is an improved version of #194 where 1) it uses format.sh from esp-idf and astyle instead of clang-format and 2) find-files is renamed to tag-files and more generic.

This adds two tools: tools/code-style and tools/tag-files. The first is
the main tool to be used by developers, the second is a utility used by
the first.

tools/code-style can replace tabs with spaces and run astyle.

tools/tag-files will list files and tag each file accoring to the
configuration file. The file patterns are configured in
tools/code-style.ini

README.md is updated with some information on the code style and how to
run the reformat tool.

[trygvis]

Rebased on top of master.

@wujiangang Is this kind of changes something that you will accept? I'm happy to make changes if Espressif have some comments.

[CLAassistant]

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