[cors] Use JDK's URI class

[Playacem]

Todos:

• tests for IPv4 addresses as an origin
• tests for IPv6 addresses as an origin
• harden port extraction especially for IPv6 addresses
• Use URI class for port logic
• complete plugin tests for IP address based origins

Fixes #2138 (once its done)

[codecov]

Codecov Report

Attention: Patch coverage is 86.48649% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 86.53%. Comparing base (01a6d55) to head (34371f6).

❗ Current head 34371f6 differs from pull request most recent head 6d6d995

Please upload reports for the commit 6d6d995 to get more accurate results.

Files	Patch %	Lines
...c/main/java/io/javalin/plugin/bundled/CorsUtils.kt	87.09%	0 Missing and 4 partials ⚠️
.../main/java/io/javalin/plugin/bundled/CorsPlugin.kt	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2180      +/-   ##
============================================
+ Coverage     86.42%   86.53%   +0.11%     
- Complexity     1299     1317      +18     
============================================
  Files           148      148              
  Lines          4029     4055      +26     
  Branches        504      513       +9     
============================================
+ Hits           3482     3509      +27     
+ Misses          331      329       -2     
- Partials        216      217       +1     

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