#24908: Validate saved files and alert user

[krasko78]

Resolves: #24908

Initial commit to demonstrate the idea and start refining it.

• [X] I signed the CLA
• [X] The title of the PR describes the problem it addresses
• [X] Each commit's message describes its purpose and effects, and references the issue it resolves
• [X] If changes are extensive, there is a sequence of easily reviewable commits
• [X] The code in the PR follows the coding rules
• [X] There are no unnecessary changes
• [X] The code compiles and runs on my machine, preferably after each commit individually
• [ ] I created a unit test or vtest to verify the changes I made (if applicable)