[roll] Roll fuchsia [fidl][fidlc] Fix modifier parser bug

The prior code would include leading attribute lists in the span for the
unknown interactions modifiers, so for examples we might get a protocol
modifier span of `@attr open` for the declaration `@attr open protocol
MyProtocol {};`.

The issue has been fixed, and span testing has been modified to take
place with the unknown interaction flag flipped on going forward.

Test: fx test fidl-test
Original-Bug: 114357, 88366
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/776325
Original-Revision: bff300df9259cd685882862f2688cbbf6a3d7fbe
GitOrigin-RevId: a07d524d107a980d8880ffd04005365385f147d6
Change-Id: Idd85826d61cb30979a25499e3b89ba7dd76b7653
diff --git a/stem b/stem
index 8cb5a5b..f8cda5d 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="97d27120cff2685fa07c158f4f76e1df15f355c6"/>
+             revision="bff300df9259cd685882862f2688cbbf6a3d7fbe"/>
   </projects>
   <hooks>
     <hook name="install-environment"