SPARQL 1.2: rdf:dirLangString with DATATYPE, CONCAT and CONTAINS

[Tpt]

Covers argument compatibility

[afs]

There are more cases such as
CONCAT("abc"@en--ltr, "xyz"@en--rtl) (-> xsd:string)
CONCAT("abc"@en--ltr, "xyz"@en) (-> xsd:string, and not @en)
CONTAINS("abc"@en--ltr, "a"@en) (->incompatible)

I'll sort out a collection of these.

[Tpt]

Thank you @afs. The test pass in Oxigraph after fixing a typo: 570238e