Add An Example Of Custom Queries Over RPC

[opticyclic]

In the original example repo there was an example of using custom queries:
https://github.com/corda/cordapp-example/blob/release-V4/java-source/src/main/java/com/example/api/ExampleApi.java#L132-L137

    QueryCriteria generalCriteria = new QueryCriteria.VaultQueryCriteria(Vault.StateStatus.ALL);
    FieldInfo lenderField = QueryCriteriaUtils.getField("lender", IOUSchemaV1.PersistentIOU.class);
    CriteriaExpression lenderIndex = Builder.equal(lenderField, myLegalName.toString());
    QueryCriteria lenderCriteria = new QueryCriteria.VaultCustomQueryCriteria(lenderIndex);
    QueryCriteria criteria = generalCriteria.and(lenderCriteria);
    List<StateAndRef<IOUState>> results = rpcOps.vaultQueryByCriteria(criteria,IOUState.class).getStates();

There doesn't appear to be a similar example in this repo.