Clean up Notion backup files

What it does:

cleanup-notion.sh does the following:

Removes UUID (Universally Unique Identifier), i.e., space + 32-digit alphanumeric characters, from filenames and directory names and their references in *.md and *.csv contents.
make failed.txt which contains the list of files and directories that failed to be renamed.
(Need to uncomment replace_space) Replace %20 with _ in filenames and directory names and their references in *.md and *.csv contents.
```
 main() {
 	remove_UUID
 	# replace_space
 	notice
 }
```

Since the script is supposed to be run on MacOS, you may need to modify something if you gonna run it on a different OS.

Please make a copy of your Exported directory before executing this script just in case!
You might have files or directories with the same name except UUID in the same directory, in that case, their links in .md files won't work after executing the script. I recommend that you rename those files before exporting from notion.

Put the unzipped notion backup as follows;

 cleanup-notion
 	|
 	|-- cleanup-notion.sh
 	|-- Export-...