Use Jsonable.fromString() in ConnectionState for consistency

[Copilot]

ConnectionState.fromString() used a custom implementation while other enums in the video package (BroadcastStatus, ArchiveStatus, VideoType) consistently use Jsonable.fromString().

Changes

• Replace custom valueOf(state.toUpperCase()) logic with Jsonable.fromString(value, ConnectionState.class)
• Add Jsonable import
• Update method parameter name from state to value to match convention
• Add Javadoc matching pattern used in other video enums

// Before
@JsonCreator
public static ConnectionState fromString(String state) {
    if (state == null) return null;
    try {
        return ConnectionState.valueOf(state.toUpperCase());
    }
    catch (IllegalArgumentException ex) {
        return null;
    }
}

// After
@JsonCreator
public static ConnectionState fromString(String value) {
    return Jsonable.fromString(value, ConnectionState.class);
}

Functionality is preserved - both implementations handle null, case conversion, and invalid values identically.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.93%. Comparing base (512e04c) to head (a3e3e2d).

Additional details and impacted files

@@                           Coverage Diff                           @@
##             devx-10296-list-video-connections     #611      +/-   ##
=======================================================================
+ Coverage                                98.90%   98.93%   +0.03%     
  Complexity                                3622     3622              
=======================================================================
  Files                                      545      545              
  Lines                                     8007     8004       -3     
  Branches                                   443      443              
=======================================================================
  Hits                                      7919     7919              
+ Misses                                      66       64       -2     
+ Partials                                    22       21       -1     

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