fix(titleCase): insert extra space when convert valid string

[ntnyq]

This PR resolves #96 and adds test cases for other converters while convert valid string.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (32ee7f5) to head (a9cbd9a). Report is 17 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #97   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines          340       409   +69     
  Branches        39        45    +6     
=========================================
+ Hits           340       409   +69     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests
• JS Bundle Analysis - Avoid shipping oversized bundles