[roll] Roll fuchsia [fx][set] Fix bug when using --fint-params-path

`args.buildDir` is empty users don't set `--dir` when
`--fint-params-path` is set, which effectively sets the GN gen dir
(ninja build dir) to FUCHSIA_DIR, causing very confusing failures later
on in `gn gen`.

This changes adds some check and failure messages to provide clearer
guidance.

To repro the failure without this change:

> fx set --fint-params-path 'integration/infra/config/generated/fuchsia/fint_params/try/minimal.arm64-release-build_only.textproto' --skip-local-args

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1262024
Original-Revision: 4cc9a256bc0245fa5afd80c4b0c16ea992c9bdec
GitOrigin-RevId: 43b53d4ddf5e8dcf269bc7bf6e6eb7918fe6b1f6
Change-Id: Icc43656d9381be13353e57ff8841723836ebde6a

stem

diff --git a/stem b/stem
index ff5c822..93893b2 100644
--- a/stem
+++ b/stem
@@ -8,7 +8,7 @@
              root=""
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="3f0a475c2d40f7e1ffa31f8beccb2d2250a9e862"
+             revision="4cc9a256bc0245fa5afd80c4b0c16ea992c9bdec"
              />
   </imports>
 </manifest>