[3.x] Support pages with more output file extensions (TextPage class)

[emmadesilva]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (51774e1) to head (e617706).
⚠️ Report is 3 commits behind head on v3/non-html-pages.

Additional details and impacted files

@@ Coverage Diff @@## v3/non-html-pages #2527 +/- ##
=====================================================
Coverage 100.00% 100.00% Complexity 1736 1736 =====================================================
Files 175 175 Lines 4336 4336 =====================================================
Hits 4336 4336 

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.