[jOOQ/jOOQ#10880] Add DECFLOAT support

This includes:

- Support casts
- Support DDL
- Support MULTISET usage
- Support Db2's NAN (all uppercase) syntax

jOOQ/src/main/java/org/jooq/Decfloat.java

@@ -188,28 +188,27 @@ public final class Decfloat extends Number implements Data {
         if (coefficient != null || special != null)
             return;
 
-        switch (data) {
-            case "+NaN":
-            case "NaN":
+        String lc;
+        switch (lc = data.toLowerCase()) {
+            case "+nan":
+            case "nan":
                 special = Special.NAN;
                 break;
 
-            case "+Infinity":
-            case "Infinity":
-            case "+Inf":
-            case "Inf":
+            case "+infinity":
+            case "infinity":
+            case "+inf":
+            case "inf":
                 special = Special.POSITIVE_INFINITY;
                 break;
 
-            case "-Infinity":
-            case "-Inf":
+            case "-infinity":
+            case "-inf":
                 special = Special.NEGATIVE_INFINITY;
                 break;
 
             default: {
-                int i = data.indexOf("E");
-                if (i == -1)
-                    i = data.indexOf("e");
+                int i = lc.indexOf("e");
 
                 try {
                     if (i == -1) {

jOOQ/src/main/java/org/jooq/impl/Multiset.java

@@ -593,6 +593,17 @@ final class Multiset<R extends Record> extends AbstractField<Result<R>> implemen
 
     @SuppressWarnings("unchecked")
     static final Field<?> castForJSON(Context<?> ctx, Field<?> field) {
+        DataType<?> t = field.getDataType();
+
+        // [#10880] Many dialects don't support NaN and other float values in JSON documents as numbers
+        if (t.isDecimal() && t.isFloat()) {
+            switch (ctx.family()) {
+
+                case H2:
+                    return field.cast(VARCHAR);
+            }
+        }
+