When the WASM UDFs were first introduced, the LANGUAGE required in
the CQL statements to use them was "xwasm", because the ABI for the
UDFs was still not specified and changes to it could be backwards
incompatible.
Now, the ABI is stabilized, but if backwards incompatible changes
are made in the future, we will add a new ABI version for them, so
the name "xwasm" is no longer needed and we can finally
change it to "wasm".
Closes#13089
The WASM UDF implementation has changed since the last time the docs
were written. In particular, the Rust helper library has been
released, and using it should be the recommended method.
Some decisions that were only experimental at the start, were also
"set in stone", so we should refer to them as such.
The docs also contain some code examples. This patch adds tests for
these examples to make sure that they are not wrong and misleading.
Closes#12941
