Fix JS client references to missing UpdaterConstants path constants

[leumor]

Summary

The GWT/JS generator sources under tools/generator/js/ reference uppercase path constants such as UpdaterConstants.DATA_PATH, UpdaterConstants.LEAVING_PATH, etc., but tools/generator/js/src/freenet/client/UpdaterConstants.java still defines only the older lowercase fields (dataPath, leavingPath, …). This causes compilation failures due to unresolved symbols.

Where

• tools/generator/js/src/freenet/client/update/DefaultUpdateManager.java:68-72
  • Uses UpdaterConstants.DATA_PATH
• tools/generator/js/src/freenet/client/UpdaterConstants.java:37-48
  • Defines only lowercase fields like dataPath, leavingPath, etc.

Other call sites also use the uppercase names (examples):

• tools/generator/js/src/freenet/client/FreenetJs.java (e.g., LEAVING_PATH, LOG_WRITEBACK_PATH)
• tools/generator/js/src/freenet/client/connection/* (e.g., NOTIFICATION_PATH, KEEPALIVE_PATH, FAILOVER_PATH)
• tools/generator/js/src/freenet/client/messages/MessageManager.java (e.g., DISMISS_ALERT_PATH)

Impact

Building/compiling the JS generator sources fails with errors similar to:

• cannot find symbol: variable DATA_PATH
• cannot find symbol: variable LEAVING_PATH

Suggested fix

Bring tools/generator/js/src/freenet/client/UpdaterConstants.java back into sync with current usage:

• Add the missing uppercase *_PATH constants (and any other renamed constants) expected by the JS sources, or
• Regenerate UpdaterConstants from the authoritative constants source/template so the generated output matches current code.

Optional: keep the old lowercase fields as deprecated aliases if anything external still depends on them.

Acceptance criteria

• tools/generator/js/src/freenet/client/** compiles without unresolved UpdaterConstants.* symbol errors.
• All path constants referenced by JS client sources exist in UpdaterConstants with the expected names.