fix(core): convert Arrow Text wrappers to ExprStringValue

PPL queries that route through the analytics-engine path can return Arrow
{@code org.apache.arrow.vector.util.Text} instances inside Map and List
fields (e.g. the {@code tokens} map of {@code patterns ...
show_numbered_token=true}). Arrow's Text class extends ReusableByteArray
and does not implement CharSequence, so the existing String branch in
{@code ExprValueUtils.fromObjectValue} doesn't match it and the fallback
throws "unsupported object class org.apache.arrow.vector.util.Text".

Detect the type by class name (avoids adding arrow-vector to the
{@code core} module's dependency graph just for one instanceof) and treat
it the same as a plain Java String.

Test impact: CalcitePPLPatternsIT 4/15 → 8/15 via the analytics-engine
route — all four SIMPLE pattern {@code show_numbered_token=true} variants
deserialize their result rows correctly now. Pairs with the OpenSearch
side commit that adds per-field {@code pattern_parser_get_pattern} /
{@code pattern_parser_get_tokens} scalar UDFs.

Signed-off-by: Kai Huang <ahkcs@amazon.com>

Author: ahkcs

core/src/main/java/org/opensearch/sql/data/model/ExprValueUtils.java

@@ -143,6 +143,15 @@ public static ExprValue fromObjectValue(Object o) {
       return new ExprDoubleValue(d);
     } else if (o instanceof String) {
       return stringValue((String) o);
+    } else if ("org.apache.arrow.vector.util.Text".equals(o.getClass().getName())) {
+      // Arrow string values inside Maps/Lists come back as Text wrappers
+      // ({@code org.apache.arrow.vector.util.Text} extends ReusableByteArray
+      // and does NOT implement CharSequence). Treat them the same as plain
+      // Strings — observed first from PPL {@code patterns ...
+      // show_numbered_token=true} where the tokens map's value-lists hold
+      // Text instead of String. Class-name check avoids adding the
+      // arrow-vector dep to {@code core} just for this one isinstance.
+      return stringValue(o.toString());
     } else if (o instanceof Float f) {
       if (!Float.isFinite(f)) {
         return LITERAL_NULL;