test: Added a test that fails when a folder contains the equals sign

[maarekj]

Add a test for verify the issue https://github.com/dotansimha/graphql-code-generator/issues/8978

Description

There is a bug with the generator when there is an equals sign in a folder name. All files inside the folder are ignored. This PR adds a test (which currently fails), to verify that these files are not skipped

Related #8978

Type of change

Please delete options that are not relevant.

• [x] Add test for a bug
• [ ] Fix the bug

Checklist:

• [x] I have followed the CONTRIBUTING doc and the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [ ] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules