Enable non-match queries in custom filters

filterManager.add assumes that if it finds a filter that has a query
prop, then it must also have a match clause contained in that query.

User created custom filters may use term queries, range queries and
the like. Once you've added any filters without a match clause like
that,
you can no longer add new filters by clicking the "add filter" icon
next to a field in the results. Instead you'll get an error that says
"Cannot read property '<your-prop>' of undefined" when filterManager.add
iterates over your custom filter with no match key.

Fixes: elastic#7246
Related: elastic#8038

src/ui/public/filter_manager/filter_manager.js

@@ -23,7 +23,7 @@ export default function (Private) {
           return filter.exists.field === value;
         }
 
-        if (filter.query) {
+        if (filter.query && filter.query.match) {
           return filter.query.match[fieldName] && filter.query.match[fieldName].query === value;
         }