Use anyOf when @allow-other = 'yes' in JSON Schema

When there is a type and an enumeration in JSON Schema, using `allOf`
means that a value must satisfy _both_ types. This is appropriate when
`@allow-other = 'no'` because it effectively limits the permitted values
to the enumeration; however, when `@allow-other = 'yes'`, that
limitation means that you are not able to use 'locally defined' values.
In this case, `anyOf` is preferable, this allows values in the
enumeration and otherwise any value that matches the schema for the
type.

A check is added explicitly for `@allow-other = 'yes'` as
`@allow-other = 'no'` is the default and matches the existing behavior.

toolchains/xslt-M4/schema-gen/make-json-schema-metamap.xsl

@@ -194,6 +194,16 @@
             <xsl:apply-templates select="$decl/constraint/allowed-values"/>
         </xsl:variable>
         <xsl:choose>
+            <xsl:when test="exists($enumerations) and $decl/constraint/allowed-values/@allow-other = 'yes'">
+                <array key="anyOf">
+                    <map>
+                        <xsl:apply-templates select="." mode="object-type"/>
+                    </map>
+                    <map>
+                        <xsl:sequence select="$enumerations"/>
+                    </map>
+                </array>
+            </xsl:when>
             <xsl:when test="exists($enumerations)">
                 <array key="allOf">
                     <map>