Create a bot to monitor changes for touching security sensitive code

See https://contribute.qt-project.org/quips/23

A bot should monitor for code changes to security-sensitive files. Take action on the following points:

• If a security header is modified, especially if severity is reduced
• If non-comment changes occur in the files

The bot should post a summary of changes to sensitive files to a teams channel.
The bot should add a "security_sensitive" hashtag to the change.