[ADQL] Add an option to FeatureSet to allow/forbid non-declared UDFs.

src/adql/parser/ADQLParser200.java

src/adql/parser/ADQLParser201.java

src/adql/parser/adqlGrammar200.jj

src/adql/parser/adqlGrammar201.jj

src/adql/parser/feature/FeatureSet.java

test/adql/parser/feature/TestFeatureSet.java