Resolves #6186

Short description 📝

Add an extra check to filter out paths that are directories (but not with a source compatible extension) when filtering source file paths.
This prevents directories with name ends with extension like .Swift being considered as source files.

How to test the changes locally 🧐

1. Add ApprovalTest.Swift package in Tuist/Package.swift

.package(url: "https://github.com/approvals/ApprovalTests.Swift.git", branch: "master")

2. Add ApprovalTest.Swift as an external dependency to one of project targets.
3. Run tuist install
4. Run tuist generate

Contributor checklist ✅

• The code has been linted using run mise run lint:fix
• The change is tested via unit testing or acceptance testing, or both
• The title of the PR is formulated in a way that is usable as a changelog entry
• In case the PR introduces changes that affect users, the documentation has been updated

Reviewer checklist ✅

• The code architecture and patterns are consistent with the rest of the codebase
• Reviewer has checked that, if needed, the PR includes the label changelog:added, changelog:fixed, or changelog:changed, and the title is usable as a changelog entry