Decode the encoded url lang input before splitting

[mpmadhavig]

Purpose

As issue has occurred when multiple languages are set as the ui_lang query param, the first item doesn't get picked up when setting ui_lang cookie.

The root cause was we have encoded the url query param before processing it [1].

With this fix, we decode the encoded query param value before making the split operation.

[1] #4826

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 41.98%. Comparing base (771f628) to head (7c847ad).
Report is 526 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7437      +/-   ##
==========================================
+ Coverage   36.53%   41.98%   +5.45%     
==========================================
  Files          42       42              
  Lines         906      936      +30     
  Branches      223      233      +10     
==========================================
+ Hits          331      393      +62     
+ Misses        555      524      -31     
+ Partials       20       19       -1     

Flag	Coverage Δ
@wso2is/core	41.98% <ø> (+5.45%)	⬆️

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see 2 files with indirect coverage changes

[wso2-jenkins-bot]

🦋 Changeset detected

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