Add descriptor class and recursirve OCI layout copy

[jonesbusy]

Description

Add descriptor class and recursirve OCI layout copy

Testing done

CI

Submitter checklist

• I have read and understood the CONTRIBUTING guide
• I have run mvn license:update-file-header, mvn spotless:apply, pre-commit run -a, mvn clean install before opening the PR

[codecov]

Codecov Report

Attention: Patch coverage is 92.59259% with 2 lines in your changes missing coverage. Please review.

Project coverage is 85.14%. Comparing base (b6d4fd6) to head (1fbd135).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/main/java/land/oras/Config.java	66.66%	0 Missing and 1 partial ⚠️
src/main/java/land/oras/Registry.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #200      +/-   ##
============================================
- Coverage     85.15%   85.14%   -0.01%     
+ Complexity      385      380       -5     
============================================
  Files            30       31       +1     
  Lines          1307     1286      -21     
  Branches        139      141       +2     
============================================
- Hits           1113     1095      -18     
+ Misses          129      126       -3     
  Partials         65       65              

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