Added url encoding to getLangUrl function

[Vainonen]

Reasons for creating this PR

Fixes made in PR #1307 caused that changing UI language broke URLs containing colons from language change links in top bar.

Link to relevant issue(s), if any

• Closes Switching language breaks ?uri= request parameter #1537

Description of the changes in this PR

Now URLs in top bar are URL encoded (except equal sign and ampersand) and should contain only encoded colons that are not omitted.

Known problems or uncertainties in this PR

If URL contains equal signs and ampersands as values that should be escaped they are not URL encoded as should be.

Checklist

• phpUnit tests pass locally with my changes
• I have added tests that show that the new code works, or tests are not relevant for this PR (e.g. only HTML/CSS changes)
• The PR doesn't reduce accessibility of the front-end code (e.g. tab focus, scaling to different resolutions, use of .sr-only class, color contrast)
• The PR doesn't introduce unintended code changes (e.g. empty lines or useless reindentation)

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (99448fc) 70.08% compared to head (65e89cd) 70.26%.
Report is 6 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1542      +/-   ##
============================================
+ Coverage     70.08%   70.26%   +0.18%     
- Complexity     1658     1668      +10     
============================================
  Files            32       32              
  Lines          4272     4298      +26     
============================================
+ Hits           2994     3020      +26     
  Misses         1278     1278              

Files	Coverage Δ
model/Request.php	79.20% <100.00%> (+0.85%)	⬆️

... and 1 file with indirect coverage changes

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