Add file path validator to custom validations module

Merged Rajendra Kadam requested to merge raju249/gitlab:file-path-validator into master

What does this MR do?

Fixes #33768 (closed)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

Availability and Testing

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

  • Label as security and @ mention @gitlab-com/gl-security/appsec
  • The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
  • Security reports checked/validated by a reviewer from the AppSec team
Edited by Peter Leitzen