fix(format): stabilize fingerprints without losing inherited changes

[joaodinissf]

Closes #1534

Why the change

Saving an unchanged .format file no longer changes its fingerprints, so the format files that extend it are no longer re-indexed, while real changes still propagate through inheritance.

Special things to note

• A fingerprint now combines the resource URI with the full source text of the configuration and of every configuration it extends. The URI is part of it because generated code records inherited source locations by file name, so renaming a base must regenerate its dependents; a text-only fingerprint failed that case.
• Computing a configuration's fingerprint resolves its with reference during indexing, and a configuration is now exported under its fingerprint, as its declarations already were.
• This removes the demonstrated unnecessary rebuild propagation. It does not claim to fix the reported endless Windows build loop.

Change outline

 fingerprint(declaration)
-  includes the parent EMF object's identity          # differs on every reload
+  its own token text, comments and delimiters included
 fingerprint(format configuration)
+  resource URI + complete source text, for itself and every configuration it extends
+  cycle-guarded; an unresolved base contributes its proxy URI and ends the walk

 com.avaloq.tools.ddk.xtext.format/
   resource/FormatResourceDescriptionStrategy.java   # the fingerprints above; bundle 17.3.3 → 17.3.4
 com.avaloq.tools.ddk.xtext.format.test/
+  resource/FormatResourceDescriptionStrategyTest.java   # 8 tests: reloads, cycles, bases, proxy URI
+  builder/FormatIncrementalBuildTest.java               # workspace: LF/CRLF saves, base rename, incremental = full build output

🤖 Generated with Claude Code