[estebanzimanyi]

A MEOS function returning a string whose length it writes through its
one size_t output parameter returns the string alone: the hexadecimal
WKB and EWKB writers of every type, 26 functions, among them
temporal_as_hexwkb, tspatial_as_hexewkb, set_as_hexwkb and
npoint_as_hexwkb. The length is the string's own, as GoMEOS's
tools/objectgen.py and MEOS.NET's object layer drop it, so
temporal_as_hexwkb(temp, variant) is a str, not a (str, int) pair. The generator reads the shape from the catalog, a char * return
with a size_t * in shape.outParams, the string twin of the byte buffer
returned as bytes.

Witness: the 26 writers annotated tuple[str, size_t *] and answered the
pair, so PyMEOS reads [0] at each of its twenty calls; each now
annotates str and answers the string.

Measured: generated from one catalog of MobilityDB aabe426a2e before and
after, the surfaces differ in those 26 functions alone; the smoke test
checks five annotations and that set_as_hexwkb answers the hexadecimal
form of the bytes set_as_wkb answers, and passes on the wheel built
against the libmeos of that commit, where PyMEOS on the branch of the
same name passes 4855 tests.