Add "es-ES" (Spanish-Spain) language to VK+IME extension manifest entry

for Spanish keyboard.

Prior to this patch, only "es" is specified, thus the "Spanish keyboard"
only shows up in "input methods" settings when (generic) "Spanish" is selected,
but not for "Spanish-Spain". There doesn't seem to be locale fallback logic
in place. Many other entries already specify both generic and country-specific
variants of languages when necessary.

We're fixing this for both Chrome OS and open-source Chromium OS, although the
bug only concerns Chrome OS.

Bug: 1021222
Change-Id: I99fe160a89f4dc774c88104e62c8214e75a83737
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1898897Reviewed-by: David Vallet <dvallet@chromium.org>
Reviewed-by: Shu Chen <shuchen@chromium.org>
Commit-Queue: Bao-Duy Tran <tranbaoduy@chromium.org>
Auto-Submit: Bao-Duy Tran <tranbaoduy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712891}

chrome/browser/resources/chromeos/input_method/google_xkb_manifest.json

@@ -617,7 +617,8 @@
       "id": "xkb:es::spa",
       "description": "",
       "language": [
-        "es"
+        "es",
+        "es-ES"
       ],
       "layouts": [
         "es"

chrome/browser/resources/chromeos/input_method/xkb_manifest.json

@@ -483,7 +483,8 @@
       "id": "xkb:es::spa",
       "description": "",
       "language": [
-        "es"
+        "es",
+        "es-ES"
       ],
       "layouts": [
         "es"