Add GHA checking for non-printable characters

[Yuri05]

Add a GitHub action which checks on pull request and on workflow dispatch that all markdown files in the repository do not contain non-printable characters like ZWNJ
(s. the issue #318).
This action should also check that none of the file names contains non-printable characters.

At the end, the action should create 2 annotations
a) Markdown table with all file paths (e.g. part-2/getting-started.md) where the file name contains non-printable characters
b) Markdown table with 3 columns for all occurrences of non-printable characters in Markdown files:

• Column 1: file path (e.g. part-2/getting-started.md)
• Column 2: Line number
• Column 3: Line content

The action should fail at the very end if at least 1 occurrence of non-printable characters was found either in a file name or markdown file content.